Showing 279 of 279 total issues
Unexpected string concatenation. Open
((existingProcess) ? ' Probably:\n ' + existingProcess : '')) +
- Read upRead up
- Exclude checks
Suggest using template literals instead of string concatenation. (prefer-template)
In ES2015 (ES6), we can use template literals instead of string concatenation.
var str = "Hello, " + name + "!";
/*eslint-env es6*/
var str = `Hello, ${name}!`;
Rule Details
This rule is aimed to flag usage of +
operators with strings.
Examples
Examples of incorrect code for this rule:
/*eslint prefer-template: "error"*/
var str = "Hello, " + name + "!";
var str = "Time: " + (12 * 60 * 60 * 1000);
Examples of correct code for this rule:
/*eslint prefer-template: "error"*/
/*eslint-env es6*/
var str = "Hello World!";
var str = `Hello, ${name}!`;
var str = `Time: ${12 * 60 * 60 * 1000}`;
// This is reported by `no-useless-concat`.
var str = "Hello, " + "World!";
When Not To Use It
This rule should not be used in ES3/5 environments.
In ES2015 (ES6) or later, if you don't want to be notified about string concatenation, you can safely disable this rule.
Related Rules
- [no-useless-concat](no-useless-concat.md)
- [quotes](quotes.md) Source: http://eslint.org/docs/rules/
Expected indentation of 6 spaces but found 8. Open
umdNamedDefine: true
- Read upRead up
- Exclude checks
enforce consistent indentation (indent)
There are several common guidelines which require specific indentation of nested blocks and statements, like:
function hello(indentSize, type) {
if (indentSize === 4 && type !== 'tab') {
console.log('Each next indentation will increase on 4 spaces');
}
}
These are the most common scenarios recommended in different style guides:
- Two spaces, not longer and no tabs: Google, npm, Node.js, Idiomatic, Felix
- Tabs: jQuery
- Four spaces: Crockford
Rule Details
This rule enforces a consistent indentation style. The default style is 4 spaces
.
Options
This rule has a mixed option:
For example, for 2-space indentation:
{
"indent": ["error", 2]
}
Or for tabbed indentation:
{
"indent": ["error", "tab"]
}
Examples of incorrect code for this rule with the default options:
/*eslint indent: "error"*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
Examples of correct code for this rule with the default options:
/*eslint indent: "error"*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
This rule has an object option:
-
"SwitchCase"
(default: 0) enforces indentation level forcase
clauses inswitch
statements -
"VariableDeclarator"
(default: 1) enforces indentation level forvar
declarators; can also take an object to define separate rules forvar
,let
andconst
declarations. -
"outerIIFEBody"
(default: 1) enforces indentation level for file-level IIFEs. -
"MemberExpression"
(off by default) enforces indentation level for multi-line property chains (except in variable declarations and assignments) -
"FunctionDeclaration"
takes an object to define rules for function declarations.-
parameters
(off by default) enforces indentation level for parameters in a function declaration. This can either be a number indicating indentation level, or the string"first"
indicating that all parameters of the declaration must be aligned with the first parameter. -
body
(default: 1) enforces indentation level for the body of a function declaration.
-
-
"FunctionExpression"
takes an object to define rules for function expressions.-
parameters
(off by default) enforces indentation level for parameters in a function expression. This can either be a number indicating indentation level, or the string"first"
indicating that all parameters of the expression must be aligned with the first parameter. -
body
(default: 1) enforces indentation level for the body of a function expression.
-
-
"CallExpression"
takes an object to define rules for function call expressions.-
arguments
(off by default) enforces indentation level for arguments in a call expression. This can either be a number indicating indentation level, or the string"first"
indicating that all arguments of the expression must be aligned with the first argument.
-
-
"ArrayExpression"
(default: 1) enforces indentation level for elements in arrays. It can also be set to the string"first"
, indicating that all the elements in the array should be aligned with the first element. -
"ObjectExpression"
(default: 1) enforces indentation level for properties in objects. It can be set to the string"first"
, indicating that all properties in the object should be aligned with the first property.
Level of indentation denotes the multiple of the indent specified. Example:
- Indent of 4 spaces with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 8 spaces. - Indent of 2 spaces with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 4 spaces. - Indent of 2 spaces with
VariableDeclarator
set to{"var": 2, "let": 2, "const": 3}
will indent the multi-line variable declarations with 4 spaces forvar
andlet
, 6 spaces forconst
statements. - Indent of tab with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 2 tabs. - Indent of 2 spaces with
SwitchCase
set to0
will not indentcase
clauses with respect toswitch
statements. - Indent of 2 spaces with
SwitchCase
set to1
will indentcase
clauses with 2 spaces with respect toswitch
statements. - Indent of 2 spaces with
SwitchCase
set to2
will indentcase
clauses with 4 spaces with respect toswitch
statements. - Indent of tab with
SwitchCase
set to2
will indentcase
clauses with 2 tabs with respect toswitch
statements. - Indent of 2 spaces with
MemberExpression
set to0
will indent the multi-line property chains with 0 spaces. - Indent of 2 spaces with
MemberExpression
set to1
will indent the multi-line property chains with 2 spaces. - Indent of 2 spaces with
MemberExpression
set to2
will indent the multi-line property chains with 4 spaces. - Indent of 4 spaces with
MemberExpression
set to0
will indent the multi-line property chains with 0 spaces. - Indent of 4 spaces with
MemberExpression
set to1
will indent the multi-line property chains with 4 spaces. - Indent of 4 spaces with
MemberExpression
set to2
will indent the multi-line property chains with 8 spaces.
tab
Examples of incorrect code for this rule with the "tab"
option:
/*eslint indent: ["error", "tab"]*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
Examples of correct code for this rule with the "tab"
option:
/*eslint indent: ["error", "tab"]*/
if (a) {
/*tab*/b=c;
/*tab*/function foo(d) {
/*tab*//*tab*/e=f;
/*tab*/}
}
SwitchCase
Examples of incorrect code for this rule with the 2, { "SwitchCase": 1 }
options:
/*eslint indent: ["error", 2, { "SwitchCase": 1 }]*/
switch(a){
case "a":
break;
case "b":
break;
}
Examples of correct code for this rule with the 2, { "SwitchCase": 1 }
option:
/*eslint indent: ["error", 2, { "SwitchCase": 1 }]*/
switch(a){
case "a":
break;
case "b":
break;
}
VariableDeclarator
Examples of incorrect code for this rule with the 2, { "VariableDeclarator": 1 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 1 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": 1 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 1 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": 2 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 2 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": { "var": 2, "let": 2, "const": 3 } }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": { "var": 2, "let": 2, "const": 3 } }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
outerIIFEBody
Examples of incorrect code for this rule with the options 2, { "outerIIFEBody": 0 }
:
/*eslint indent: ["error", 2, { "outerIIFEBody": 0 }]*/
(function() {
function foo(x) {
return x + 1;
}
})();
if(y) {
console.log('foo');
}
Examples of correct code for this rule with the options 2, {"outerIIFEBody": 0}
:
/*eslint indent: ["error", 2, { "outerIIFEBody": 0 }]*/
(function() {
function foo(x) {
return x + 1;
}
})();
if(y) {
console.log('foo');
}
MemberExpression
Examples of incorrect code for this rule with the 2, { "MemberExpression": 1 }
options:
/*eslint indent: ["error", 2, { "MemberExpression": 1 }]*/
foo
.bar
.baz()
Examples of correct code for this rule with the 2, { "MemberExpression": 1 }
option:
/*eslint indent: ["error", 2, { "MemberExpression": 1 }]*/
foo
.bar
.baz();
// Any indentation is permitted in variable declarations and assignments.
var bip = aardvark.badger
.coyote;
FunctionDeclaration
Examples of incorrect code for this rule with the 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }]*/
function foo(bar,
baz,
qux) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }]*/
function foo(bar,
baz,
qux) {
qux();
}
Examples of incorrect code for this rule with the 2, { "FunctionDeclaration": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionDeclaration": {"parameters": "first"}}]*/
function foo(bar, baz,
qux, boop) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionDeclaration": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionDeclaration": {"parameters": "first"}}]*/
function foo(bar, baz,
qux, boop) {
qux();
}
FunctionExpression
Examples of incorrect code for this rule with the 2, { "FunctionExpression": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionExpression": {"body": 1, "parameters": 2} }]*/
var foo = function(bar,
baz,
qux) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionExpression": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionExpression": {"body": 1, "parameters": 2} }]*/
var foo = function(bar,
baz,
qux) {
qux();
}
Examples of incorrect code for this rule with the 2, { "FunctionExpression": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionExpression": {"parameters": "first"}}]*/
var foo = function(bar, baz,
qux, boop) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionExpression": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionExpression": {"parameters": "first"}}]*/
var foo = function(bar, baz,
qux, boop) {
qux();
}
CallExpression
Examples of incorrect code for this rule with the 2, { "CallExpression": {"arguments": 1} }
option:
/*eslint indent: ["error", 2, { "CallExpression": {"arguments": 1} }]*/
foo(bar,
baz,
qux
);
Examples of correct code for this rule with the 2, { "CallExpression": {"arguments": 1} }
option:
/*eslint indent: ["error", 2, { "CallExpression": {"arguments": 1} }]*/
foo(bar,
baz,
qux
);
Examples of incorrect code for this rule with the 2, { "CallExpression": {"arguments": "first"} }
option:
/*eslint indent: ["error", 2, {"CallExpression": {"arguments": "first"}}]*/
foo(bar, baz,
baz, boop, beep);
Examples of correct code for this rule with the 2, { "CallExpression": {"arguments": "first"} }
option:
/*eslint indent: ["error", 2, {"CallExpression": {"arguments": "first"}}]*/
foo(bar, baz,
baz, boop, beep);
ArrayExpression
Examples of incorrect code for this rule with the 2, { "ArrayExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ArrayExpression": 1 }]*/
var foo = [
bar,
baz,
qux
];
Examples of correct code for this rule with the 2, { "ArrayExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ArrayExpression": 1 }]*/
var foo = [
bar,
baz,
qux
];
Examples of incorrect code for this rule with the 2, { "ArrayExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ArrayExpression": "first"}]*/
var foo = [bar,
baz,
qux
];
Examples of correct code for this rule with the 2, { "ArrayExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ArrayExpression": "first"}]*/
var foo = [bar,
baz,
qux
];
ObjectExpression
Examples of incorrect code for this rule with the 2, { "ObjectExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ObjectExpression": 1 }]*/
var foo = {
bar: 1,
baz: 2,
qux: 3
};
Examples of correct code for this rule with the 2, { "ObjectExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ObjectExpression": 1 }]*/
var foo = {
bar: 1,
baz: 2,
qux: 3
};
Examples of incorrect code for this rule with the 2, { "ObjectExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ObjectExpression": "first"}]*/
var foo = { bar: 1,
baz: 2 };
Examples of correct code for this rule with the 2, { "ObjectExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ObjectExpression": "first"}]*/
var foo = { bar: 1,
baz: 2 };
Compatibility
-
JSHint:
indent
- JSCS: validateIndentation Source: http://eslint.org/docs/rules/
Unexpected var, use let or const instead. Open
var plugins = [], outputFile;
- Read upRead up
- Exclude checks
require let
or const
instead of var
(no-var)
ECMAScript 6 allows programmers to create variables with block scope instead of function scope using the let
and const
keywords. Block scope is common in many other programming languages and helps programmers avoid mistakes
such as:
var count = people.length;
var enoughFood = count > sandwiches.length;
if (enoughFood) {
var count = sandwiches.length; // accidentally overriding the count variable
console.log("We have " + count + " sandwiches for everyone. Plenty for all!");
}
// our count variable is no longer accurate
console.log("We have " + count + " people and " + sandwiches.length + " sandwiches!");
Rule Details
This rule is aimed at discouraging the use of var
and encouraging the use of const
or let
instead.
Examples
Examples of incorrect code for this rule:
/*eslint no-var: "error"*/
var x = "y";
var CONFIG = {};
Examples of correct code for this rule:
/*eslint no-var: "error"*/
/*eslint-env es6*/
let x = "y";
const CONFIG = {};
When Not To Use It
In addition to non-ES6 environments, existing JavaScript projects that are beginning to introduce ES6 into their
codebase may not want to apply this rule if the cost of migrating from var
to let
is too costly.
Source: http://eslint.org/docs/rules/
Unexpected string concatenation. Open
path: __dirname + '/dist',
- Read upRead up
- Exclude checks
Suggest using template literals instead of string concatenation. (prefer-template)
In ES2015 (ES6), we can use template literals instead of string concatenation.
var str = "Hello, " + name + "!";
/*eslint-env es6*/
var str = `Hello, ${name}!`;
Rule Details
This rule is aimed to flag usage of +
operators with strings.
Examples
Examples of incorrect code for this rule:
/*eslint prefer-template: "error"*/
var str = "Hello, " + name + "!";
var str = "Time: " + (12 * 60 * 60 * 1000);
Examples of correct code for this rule:
/*eslint prefer-template: "error"*/
/*eslint-env es6*/
var str = "Hello World!";
var str = `Hello, ${name}!`;
var str = `Time: ${12 * 60 * 60 * 1000}`;
// This is reported by `no-useless-concat`.
var str = "Hello, " + "World!";
When Not To Use It
This rule should not be used in ES3/5 environments.
In ES2015 (ES6) or later, if you don't want to be notified about string concatenation, you can safely disable this rule.
Related Rules
- [no-useless-concat](no-useless-concat.md)
- [quotes](quotes.md) Source: http://eslint.org/docs/rules/
Expected indentation of 6 spaces but found 8. Open
libraryTarget: 'umd',
- Read upRead up
- Exclude checks
enforce consistent indentation (indent)
There are several common guidelines which require specific indentation of nested blocks and statements, like:
function hello(indentSize, type) {
if (indentSize === 4 && type !== 'tab') {
console.log('Each next indentation will increase on 4 spaces');
}
}
These are the most common scenarios recommended in different style guides:
- Two spaces, not longer and no tabs: Google, npm, Node.js, Idiomatic, Felix
- Tabs: jQuery
- Four spaces: Crockford
Rule Details
This rule enforces a consistent indentation style. The default style is 4 spaces
.
Options
This rule has a mixed option:
For example, for 2-space indentation:
{
"indent": ["error", 2]
}
Or for tabbed indentation:
{
"indent": ["error", "tab"]
}
Examples of incorrect code for this rule with the default options:
/*eslint indent: "error"*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
Examples of correct code for this rule with the default options:
/*eslint indent: "error"*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
This rule has an object option:
-
"SwitchCase"
(default: 0) enforces indentation level forcase
clauses inswitch
statements -
"VariableDeclarator"
(default: 1) enforces indentation level forvar
declarators; can also take an object to define separate rules forvar
,let
andconst
declarations. -
"outerIIFEBody"
(default: 1) enforces indentation level for file-level IIFEs. -
"MemberExpression"
(off by default) enforces indentation level for multi-line property chains (except in variable declarations and assignments) -
"FunctionDeclaration"
takes an object to define rules for function declarations.-
parameters
(off by default) enforces indentation level for parameters in a function declaration. This can either be a number indicating indentation level, or the string"first"
indicating that all parameters of the declaration must be aligned with the first parameter. -
body
(default: 1) enforces indentation level for the body of a function declaration.
-
-
"FunctionExpression"
takes an object to define rules for function expressions.-
parameters
(off by default) enforces indentation level for parameters in a function expression. This can either be a number indicating indentation level, or the string"first"
indicating that all parameters of the expression must be aligned with the first parameter. -
body
(default: 1) enforces indentation level for the body of a function expression.
-
-
"CallExpression"
takes an object to define rules for function call expressions.-
arguments
(off by default) enforces indentation level for arguments in a call expression. This can either be a number indicating indentation level, or the string"first"
indicating that all arguments of the expression must be aligned with the first argument.
-
-
"ArrayExpression"
(default: 1) enforces indentation level for elements in arrays. It can also be set to the string"first"
, indicating that all the elements in the array should be aligned with the first element. -
"ObjectExpression"
(default: 1) enforces indentation level for properties in objects. It can be set to the string"first"
, indicating that all properties in the object should be aligned with the first property.
Level of indentation denotes the multiple of the indent specified. Example:
- Indent of 4 spaces with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 8 spaces. - Indent of 2 spaces with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 4 spaces. - Indent of 2 spaces with
VariableDeclarator
set to{"var": 2, "let": 2, "const": 3}
will indent the multi-line variable declarations with 4 spaces forvar
andlet
, 6 spaces forconst
statements. - Indent of tab with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 2 tabs. - Indent of 2 spaces with
SwitchCase
set to0
will not indentcase
clauses with respect toswitch
statements. - Indent of 2 spaces with
SwitchCase
set to1
will indentcase
clauses with 2 spaces with respect toswitch
statements. - Indent of 2 spaces with
SwitchCase
set to2
will indentcase
clauses with 4 spaces with respect toswitch
statements. - Indent of tab with
SwitchCase
set to2
will indentcase
clauses with 2 tabs with respect toswitch
statements. - Indent of 2 spaces with
MemberExpression
set to0
will indent the multi-line property chains with 0 spaces. - Indent of 2 spaces with
MemberExpression
set to1
will indent the multi-line property chains with 2 spaces. - Indent of 2 spaces with
MemberExpression
set to2
will indent the multi-line property chains with 4 spaces. - Indent of 4 spaces with
MemberExpression
set to0
will indent the multi-line property chains with 0 spaces. - Indent of 4 spaces with
MemberExpression
set to1
will indent the multi-line property chains with 4 spaces. - Indent of 4 spaces with
MemberExpression
set to2
will indent the multi-line property chains with 8 spaces.
tab
Examples of incorrect code for this rule with the "tab"
option:
/*eslint indent: ["error", "tab"]*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
Examples of correct code for this rule with the "tab"
option:
/*eslint indent: ["error", "tab"]*/
if (a) {
/*tab*/b=c;
/*tab*/function foo(d) {
/*tab*//*tab*/e=f;
/*tab*/}
}
SwitchCase
Examples of incorrect code for this rule with the 2, { "SwitchCase": 1 }
options:
/*eslint indent: ["error", 2, { "SwitchCase": 1 }]*/
switch(a){
case "a":
break;
case "b":
break;
}
Examples of correct code for this rule with the 2, { "SwitchCase": 1 }
option:
/*eslint indent: ["error", 2, { "SwitchCase": 1 }]*/
switch(a){
case "a":
break;
case "b":
break;
}
VariableDeclarator
Examples of incorrect code for this rule with the 2, { "VariableDeclarator": 1 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 1 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": 1 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 1 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": 2 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 2 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": { "var": 2, "let": 2, "const": 3 } }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": { "var": 2, "let": 2, "const": 3 } }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
outerIIFEBody
Examples of incorrect code for this rule with the options 2, { "outerIIFEBody": 0 }
:
/*eslint indent: ["error", 2, { "outerIIFEBody": 0 }]*/
(function() {
function foo(x) {
return x + 1;
}
})();
if(y) {
console.log('foo');
}
Examples of correct code for this rule with the options 2, {"outerIIFEBody": 0}
:
/*eslint indent: ["error", 2, { "outerIIFEBody": 0 }]*/
(function() {
function foo(x) {
return x + 1;
}
})();
if(y) {
console.log('foo');
}
MemberExpression
Examples of incorrect code for this rule with the 2, { "MemberExpression": 1 }
options:
/*eslint indent: ["error", 2, { "MemberExpression": 1 }]*/
foo
.bar
.baz()
Examples of correct code for this rule with the 2, { "MemberExpression": 1 }
option:
/*eslint indent: ["error", 2, { "MemberExpression": 1 }]*/
foo
.bar
.baz();
// Any indentation is permitted in variable declarations and assignments.
var bip = aardvark.badger
.coyote;
FunctionDeclaration
Examples of incorrect code for this rule with the 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }]*/
function foo(bar,
baz,
qux) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }]*/
function foo(bar,
baz,
qux) {
qux();
}
Examples of incorrect code for this rule with the 2, { "FunctionDeclaration": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionDeclaration": {"parameters": "first"}}]*/
function foo(bar, baz,
qux, boop) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionDeclaration": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionDeclaration": {"parameters": "first"}}]*/
function foo(bar, baz,
qux, boop) {
qux();
}
FunctionExpression
Examples of incorrect code for this rule with the 2, { "FunctionExpression": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionExpression": {"body": 1, "parameters": 2} }]*/
var foo = function(bar,
baz,
qux) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionExpression": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionExpression": {"body": 1, "parameters": 2} }]*/
var foo = function(bar,
baz,
qux) {
qux();
}
Examples of incorrect code for this rule with the 2, { "FunctionExpression": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionExpression": {"parameters": "first"}}]*/
var foo = function(bar, baz,
qux, boop) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionExpression": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionExpression": {"parameters": "first"}}]*/
var foo = function(bar, baz,
qux, boop) {
qux();
}
CallExpression
Examples of incorrect code for this rule with the 2, { "CallExpression": {"arguments": 1} }
option:
/*eslint indent: ["error", 2, { "CallExpression": {"arguments": 1} }]*/
foo(bar,
baz,
qux
);
Examples of correct code for this rule with the 2, { "CallExpression": {"arguments": 1} }
option:
/*eslint indent: ["error", 2, { "CallExpression": {"arguments": 1} }]*/
foo(bar,
baz,
qux
);
Examples of incorrect code for this rule with the 2, { "CallExpression": {"arguments": "first"} }
option:
/*eslint indent: ["error", 2, {"CallExpression": {"arguments": "first"}}]*/
foo(bar, baz,
baz, boop, beep);
Examples of correct code for this rule with the 2, { "CallExpression": {"arguments": "first"} }
option:
/*eslint indent: ["error", 2, {"CallExpression": {"arguments": "first"}}]*/
foo(bar, baz,
baz, boop, beep);
ArrayExpression
Examples of incorrect code for this rule with the 2, { "ArrayExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ArrayExpression": 1 }]*/
var foo = [
bar,
baz,
qux
];
Examples of correct code for this rule with the 2, { "ArrayExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ArrayExpression": 1 }]*/
var foo = [
bar,
baz,
qux
];
Examples of incorrect code for this rule with the 2, { "ArrayExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ArrayExpression": "first"}]*/
var foo = [bar,
baz,
qux
];
Examples of correct code for this rule with the 2, { "ArrayExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ArrayExpression": "first"}]*/
var foo = [bar,
baz,
qux
];
ObjectExpression
Examples of incorrect code for this rule with the 2, { "ObjectExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ObjectExpression": 1 }]*/
var foo = {
bar: 1,
baz: 2,
qux: 3
};
Examples of correct code for this rule with the 2, { "ObjectExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ObjectExpression": 1 }]*/
var foo = {
bar: 1,
baz: 2,
qux: 3
};
Examples of incorrect code for this rule with the 2, { "ObjectExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ObjectExpression": "first"}]*/
var foo = { bar: 1,
baz: 2 };
Examples of correct code for this rule with the 2, { "ObjectExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ObjectExpression": "first"}]*/
var foo = { bar: 1,
baz: 2 };
Compatibility
-
JSHint:
indent
- JSCS: validateIndentation Source: http://eslint.org/docs/rules/
Expected indentation of 10 spaces but found 12. Open
},
- Read upRead up
- Exclude checks
enforce consistent indentation (indent)
There are several common guidelines which require specific indentation of nested blocks and statements, like:
function hello(indentSize, type) {
if (indentSize === 4 && type !== 'tab') {
console.log('Each next indentation will increase on 4 spaces');
}
}
These are the most common scenarios recommended in different style guides:
- Two spaces, not longer and no tabs: Google, npm, Node.js, Idiomatic, Felix
- Tabs: jQuery
- Four spaces: Crockford
Rule Details
This rule enforces a consistent indentation style. The default style is 4 spaces
.
Options
This rule has a mixed option:
For example, for 2-space indentation:
{
"indent": ["error", 2]
}
Or for tabbed indentation:
{
"indent": ["error", "tab"]
}
Examples of incorrect code for this rule with the default options:
/*eslint indent: "error"*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
Examples of correct code for this rule with the default options:
/*eslint indent: "error"*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
This rule has an object option:
-
"SwitchCase"
(default: 0) enforces indentation level forcase
clauses inswitch
statements -
"VariableDeclarator"
(default: 1) enforces indentation level forvar
declarators; can also take an object to define separate rules forvar
,let
andconst
declarations. -
"outerIIFEBody"
(default: 1) enforces indentation level for file-level IIFEs. -
"MemberExpression"
(off by default) enforces indentation level for multi-line property chains (except in variable declarations and assignments) -
"FunctionDeclaration"
takes an object to define rules for function declarations.-
parameters
(off by default) enforces indentation level for parameters in a function declaration. This can either be a number indicating indentation level, or the string"first"
indicating that all parameters of the declaration must be aligned with the first parameter. -
body
(default: 1) enforces indentation level for the body of a function declaration.
-
-
"FunctionExpression"
takes an object to define rules for function expressions.-
parameters
(off by default) enforces indentation level for parameters in a function expression. This can either be a number indicating indentation level, or the string"first"
indicating that all parameters of the expression must be aligned with the first parameter. -
body
(default: 1) enforces indentation level for the body of a function expression.
-
-
"CallExpression"
takes an object to define rules for function call expressions.-
arguments
(off by default) enforces indentation level for arguments in a call expression. This can either be a number indicating indentation level, or the string"first"
indicating that all arguments of the expression must be aligned with the first argument.
-
-
"ArrayExpression"
(default: 1) enforces indentation level for elements in arrays. It can also be set to the string"first"
, indicating that all the elements in the array should be aligned with the first element. -
"ObjectExpression"
(default: 1) enforces indentation level for properties in objects. It can be set to the string"first"
, indicating that all properties in the object should be aligned with the first property.
Level of indentation denotes the multiple of the indent specified. Example:
- Indent of 4 spaces with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 8 spaces. - Indent of 2 spaces with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 4 spaces. - Indent of 2 spaces with
VariableDeclarator
set to{"var": 2, "let": 2, "const": 3}
will indent the multi-line variable declarations with 4 spaces forvar
andlet
, 6 spaces forconst
statements. - Indent of tab with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 2 tabs. - Indent of 2 spaces with
SwitchCase
set to0
will not indentcase
clauses with respect toswitch
statements. - Indent of 2 spaces with
SwitchCase
set to1
will indentcase
clauses with 2 spaces with respect toswitch
statements. - Indent of 2 spaces with
SwitchCase
set to2
will indentcase
clauses with 4 spaces with respect toswitch
statements. - Indent of tab with
SwitchCase
set to2
will indentcase
clauses with 2 tabs with respect toswitch
statements. - Indent of 2 spaces with
MemberExpression
set to0
will indent the multi-line property chains with 0 spaces. - Indent of 2 spaces with
MemberExpression
set to1
will indent the multi-line property chains with 2 spaces. - Indent of 2 spaces with
MemberExpression
set to2
will indent the multi-line property chains with 4 spaces. - Indent of 4 spaces with
MemberExpression
set to0
will indent the multi-line property chains with 0 spaces. - Indent of 4 spaces with
MemberExpression
set to1
will indent the multi-line property chains with 4 spaces. - Indent of 4 spaces with
MemberExpression
set to2
will indent the multi-line property chains with 8 spaces.
tab
Examples of incorrect code for this rule with the "tab"
option:
/*eslint indent: ["error", "tab"]*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
Examples of correct code for this rule with the "tab"
option:
/*eslint indent: ["error", "tab"]*/
if (a) {
/*tab*/b=c;
/*tab*/function foo(d) {
/*tab*//*tab*/e=f;
/*tab*/}
}
SwitchCase
Examples of incorrect code for this rule with the 2, { "SwitchCase": 1 }
options:
/*eslint indent: ["error", 2, { "SwitchCase": 1 }]*/
switch(a){
case "a":
break;
case "b":
break;
}
Examples of correct code for this rule with the 2, { "SwitchCase": 1 }
option:
/*eslint indent: ["error", 2, { "SwitchCase": 1 }]*/
switch(a){
case "a":
break;
case "b":
break;
}
VariableDeclarator
Examples of incorrect code for this rule with the 2, { "VariableDeclarator": 1 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 1 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": 1 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 1 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": 2 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 2 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": { "var": 2, "let": 2, "const": 3 } }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": { "var": 2, "let": 2, "const": 3 } }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
outerIIFEBody
Examples of incorrect code for this rule with the options 2, { "outerIIFEBody": 0 }
:
/*eslint indent: ["error", 2, { "outerIIFEBody": 0 }]*/
(function() {
function foo(x) {
return x + 1;
}
})();
if(y) {
console.log('foo');
}
Examples of correct code for this rule with the options 2, {"outerIIFEBody": 0}
:
/*eslint indent: ["error", 2, { "outerIIFEBody": 0 }]*/
(function() {
function foo(x) {
return x + 1;
}
})();
if(y) {
console.log('foo');
}
MemberExpression
Examples of incorrect code for this rule with the 2, { "MemberExpression": 1 }
options:
/*eslint indent: ["error", 2, { "MemberExpression": 1 }]*/
foo
.bar
.baz()
Examples of correct code for this rule with the 2, { "MemberExpression": 1 }
option:
/*eslint indent: ["error", 2, { "MemberExpression": 1 }]*/
foo
.bar
.baz();
// Any indentation is permitted in variable declarations and assignments.
var bip = aardvark.badger
.coyote;
FunctionDeclaration
Examples of incorrect code for this rule with the 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }]*/
function foo(bar,
baz,
qux) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }]*/
function foo(bar,
baz,
qux) {
qux();
}
Examples of incorrect code for this rule with the 2, { "FunctionDeclaration": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionDeclaration": {"parameters": "first"}}]*/
function foo(bar, baz,
qux, boop) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionDeclaration": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionDeclaration": {"parameters": "first"}}]*/
function foo(bar, baz,
qux, boop) {
qux();
}
FunctionExpression
Examples of incorrect code for this rule with the 2, { "FunctionExpression": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionExpression": {"body": 1, "parameters": 2} }]*/
var foo = function(bar,
baz,
qux) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionExpression": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionExpression": {"body": 1, "parameters": 2} }]*/
var foo = function(bar,
baz,
qux) {
qux();
}
Examples of incorrect code for this rule with the 2, { "FunctionExpression": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionExpression": {"parameters": "first"}}]*/
var foo = function(bar, baz,
qux, boop) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionExpression": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionExpression": {"parameters": "first"}}]*/
var foo = function(bar, baz,
qux, boop) {
qux();
}
CallExpression
Examples of incorrect code for this rule with the 2, { "CallExpression": {"arguments": 1} }
option:
/*eslint indent: ["error", 2, { "CallExpression": {"arguments": 1} }]*/
foo(bar,
baz,
qux
);
Examples of correct code for this rule with the 2, { "CallExpression": {"arguments": 1} }
option:
/*eslint indent: ["error", 2, { "CallExpression": {"arguments": 1} }]*/
foo(bar,
baz,
qux
);
Examples of incorrect code for this rule with the 2, { "CallExpression": {"arguments": "first"} }
option:
/*eslint indent: ["error", 2, {"CallExpression": {"arguments": "first"}}]*/
foo(bar, baz,
baz, boop, beep);
Examples of correct code for this rule with the 2, { "CallExpression": {"arguments": "first"} }
option:
/*eslint indent: ["error", 2, {"CallExpression": {"arguments": "first"}}]*/
foo(bar, baz,
baz, boop, beep);
ArrayExpression
Examples of incorrect code for this rule with the 2, { "ArrayExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ArrayExpression": 1 }]*/
var foo = [
bar,
baz,
qux
];
Examples of correct code for this rule with the 2, { "ArrayExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ArrayExpression": 1 }]*/
var foo = [
bar,
baz,
qux
];
Examples of incorrect code for this rule with the 2, { "ArrayExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ArrayExpression": "first"}]*/
var foo = [bar,
baz,
qux
];
Examples of correct code for this rule with the 2, { "ArrayExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ArrayExpression": "first"}]*/
var foo = [bar,
baz,
qux
];
ObjectExpression
Examples of incorrect code for this rule with the 2, { "ObjectExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ObjectExpression": 1 }]*/
var foo = {
bar: 1,
baz: 2,
qux: 3
};
Examples of correct code for this rule with the 2, { "ObjectExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ObjectExpression": 1 }]*/
var foo = {
bar: 1,
baz: 2,
qux: 3
};
Examples of incorrect code for this rule with the 2, { "ObjectExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ObjectExpression": "first"}]*/
var foo = { bar: 1,
baz: 2 };
Examples of correct code for this rule with the 2, { "ObjectExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ObjectExpression": "first"}]*/
var foo = { bar: 1,
baz: 2 };
Compatibility
-
JSHint:
indent
- JSCS: validateIndentation Source: http://eslint.org/docs/rules/
Expected indentation of 12 spaces but found 16. Open
loader: 'babel',
- Read upRead up
- Exclude checks
enforce consistent indentation (indent)
There are several common guidelines which require specific indentation of nested blocks and statements, like:
function hello(indentSize, type) {
if (indentSize === 4 && type !== 'tab') {
console.log('Each next indentation will increase on 4 spaces');
}
}
These are the most common scenarios recommended in different style guides:
- Two spaces, not longer and no tabs: Google, npm, Node.js, Idiomatic, Felix
- Tabs: jQuery
- Four spaces: Crockford
Rule Details
This rule enforces a consistent indentation style. The default style is 4 spaces
.
Options
This rule has a mixed option:
For example, for 2-space indentation:
{
"indent": ["error", 2]
}
Or for tabbed indentation:
{
"indent": ["error", "tab"]
}
Examples of incorrect code for this rule with the default options:
/*eslint indent: "error"*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
Examples of correct code for this rule with the default options:
/*eslint indent: "error"*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
This rule has an object option:
-
"SwitchCase"
(default: 0) enforces indentation level forcase
clauses inswitch
statements -
"VariableDeclarator"
(default: 1) enforces indentation level forvar
declarators; can also take an object to define separate rules forvar
,let
andconst
declarations. -
"outerIIFEBody"
(default: 1) enforces indentation level for file-level IIFEs. -
"MemberExpression"
(off by default) enforces indentation level for multi-line property chains (except in variable declarations and assignments) -
"FunctionDeclaration"
takes an object to define rules for function declarations.-
parameters
(off by default) enforces indentation level for parameters in a function declaration. This can either be a number indicating indentation level, or the string"first"
indicating that all parameters of the declaration must be aligned with the first parameter. -
body
(default: 1) enforces indentation level for the body of a function declaration.
-
-
"FunctionExpression"
takes an object to define rules for function expressions.-
parameters
(off by default) enforces indentation level for parameters in a function expression. This can either be a number indicating indentation level, or the string"first"
indicating that all parameters of the expression must be aligned with the first parameter. -
body
(default: 1) enforces indentation level for the body of a function expression.
-
-
"CallExpression"
takes an object to define rules for function call expressions.-
arguments
(off by default) enforces indentation level for arguments in a call expression. This can either be a number indicating indentation level, or the string"first"
indicating that all arguments of the expression must be aligned with the first argument.
-
-
"ArrayExpression"
(default: 1) enforces indentation level for elements in arrays. It can also be set to the string"first"
, indicating that all the elements in the array should be aligned with the first element. -
"ObjectExpression"
(default: 1) enforces indentation level for properties in objects. It can be set to the string"first"
, indicating that all properties in the object should be aligned with the first property.
Level of indentation denotes the multiple of the indent specified. Example:
- Indent of 4 spaces with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 8 spaces. - Indent of 2 spaces with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 4 spaces. - Indent of 2 spaces with
VariableDeclarator
set to{"var": 2, "let": 2, "const": 3}
will indent the multi-line variable declarations with 4 spaces forvar
andlet
, 6 spaces forconst
statements. - Indent of tab with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 2 tabs. - Indent of 2 spaces with
SwitchCase
set to0
will not indentcase
clauses with respect toswitch
statements. - Indent of 2 spaces with
SwitchCase
set to1
will indentcase
clauses with 2 spaces with respect toswitch
statements. - Indent of 2 spaces with
SwitchCase
set to2
will indentcase
clauses with 4 spaces with respect toswitch
statements. - Indent of tab with
SwitchCase
set to2
will indentcase
clauses with 2 tabs with respect toswitch
statements. - Indent of 2 spaces with
MemberExpression
set to0
will indent the multi-line property chains with 0 spaces. - Indent of 2 spaces with
MemberExpression
set to1
will indent the multi-line property chains with 2 spaces. - Indent of 2 spaces with
MemberExpression
set to2
will indent the multi-line property chains with 4 spaces. - Indent of 4 spaces with
MemberExpression
set to0
will indent the multi-line property chains with 0 spaces. - Indent of 4 spaces with
MemberExpression
set to1
will indent the multi-line property chains with 4 spaces. - Indent of 4 spaces with
MemberExpression
set to2
will indent the multi-line property chains with 8 spaces.
tab
Examples of incorrect code for this rule with the "tab"
option:
/*eslint indent: ["error", "tab"]*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
Examples of correct code for this rule with the "tab"
option:
/*eslint indent: ["error", "tab"]*/
if (a) {
/*tab*/b=c;
/*tab*/function foo(d) {
/*tab*//*tab*/e=f;
/*tab*/}
}
SwitchCase
Examples of incorrect code for this rule with the 2, { "SwitchCase": 1 }
options:
/*eslint indent: ["error", 2, { "SwitchCase": 1 }]*/
switch(a){
case "a":
break;
case "b":
break;
}
Examples of correct code for this rule with the 2, { "SwitchCase": 1 }
option:
/*eslint indent: ["error", 2, { "SwitchCase": 1 }]*/
switch(a){
case "a":
break;
case "b":
break;
}
VariableDeclarator
Examples of incorrect code for this rule with the 2, { "VariableDeclarator": 1 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 1 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": 1 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 1 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": 2 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 2 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": { "var": 2, "let": 2, "const": 3 } }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": { "var": 2, "let": 2, "const": 3 } }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
outerIIFEBody
Examples of incorrect code for this rule with the options 2, { "outerIIFEBody": 0 }
:
/*eslint indent: ["error", 2, { "outerIIFEBody": 0 }]*/
(function() {
function foo(x) {
return x + 1;
}
})();
if(y) {
console.log('foo');
}
Examples of correct code for this rule with the options 2, {"outerIIFEBody": 0}
:
/*eslint indent: ["error", 2, { "outerIIFEBody": 0 }]*/
(function() {
function foo(x) {
return x + 1;
}
})();
if(y) {
console.log('foo');
}
MemberExpression
Examples of incorrect code for this rule with the 2, { "MemberExpression": 1 }
options:
/*eslint indent: ["error", 2, { "MemberExpression": 1 }]*/
foo
.bar
.baz()
Examples of correct code for this rule with the 2, { "MemberExpression": 1 }
option:
/*eslint indent: ["error", 2, { "MemberExpression": 1 }]*/
foo
.bar
.baz();
// Any indentation is permitted in variable declarations and assignments.
var bip = aardvark.badger
.coyote;
FunctionDeclaration
Examples of incorrect code for this rule with the 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }]*/
function foo(bar,
baz,
qux) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }]*/
function foo(bar,
baz,
qux) {
qux();
}
Examples of incorrect code for this rule with the 2, { "FunctionDeclaration": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionDeclaration": {"parameters": "first"}}]*/
function foo(bar, baz,
qux, boop) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionDeclaration": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionDeclaration": {"parameters": "first"}}]*/
function foo(bar, baz,
qux, boop) {
qux();
}
FunctionExpression
Examples of incorrect code for this rule with the 2, { "FunctionExpression": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionExpression": {"body": 1, "parameters": 2} }]*/
var foo = function(bar,
baz,
qux) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionExpression": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionExpression": {"body": 1, "parameters": 2} }]*/
var foo = function(bar,
baz,
qux) {
qux();
}
Examples of incorrect code for this rule with the 2, { "FunctionExpression": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionExpression": {"parameters": "first"}}]*/
var foo = function(bar, baz,
qux, boop) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionExpression": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionExpression": {"parameters": "first"}}]*/
var foo = function(bar, baz,
qux, boop) {
qux();
}
CallExpression
Examples of incorrect code for this rule with the 2, { "CallExpression": {"arguments": 1} }
option:
/*eslint indent: ["error", 2, { "CallExpression": {"arguments": 1} }]*/
foo(bar,
baz,
qux
);
Examples of correct code for this rule with the 2, { "CallExpression": {"arguments": 1} }
option:
/*eslint indent: ["error", 2, { "CallExpression": {"arguments": 1} }]*/
foo(bar,
baz,
qux
);
Examples of incorrect code for this rule with the 2, { "CallExpression": {"arguments": "first"} }
option:
/*eslint indent: ["error", 2, {"CallExpression": {"arguments": "first"}}]*/
foo(bar, baz,
baz, boop, beep);
Examples of correct code for this rule with the 2, { "CallExpression": {"arguments": "first"} }
option:
/*eslint indent: ["error", 2, {"CallExpression": {"arguments": "first"}}]*/
foo(bar, baz,
baz, boop, beep);
ArrayExpression
Examples of incorrect code for this rule with the 2, { "ArrayExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ArrayExpression": 1 }]*/
var foo = [
bar,
baz,
qux
];
Examples of correct code for this rule with the 2, { "ArrayExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ArrayExpression": 1 }]*/
var foo = [
bar,
baz,
qux
];
Examples of incorrect code for this rule with the 2, { "ArrayExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ArrayExpression": "first"}]*/
var foo = [bar,
baz,
qux
];
Examples of correct code for this rule with the 2, { "ArrayExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ArrayExpression": "first"}]*/
var foo = [bar,
baz,
qux
];
ObjectExpression
Examples of incorrect code for this rule with the 2, { "ObjectExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ObjectExpression": 1 }]*/
var foo = {
bar: 1,
baz: 2,
qux: 3
};
Examples of correct code for this rule with the 2, { "ObjectExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ObjectExpression": 1 }]*/
var foo = {
bar: 1,
baz: 2,
qux: 3
};
Examples of incorrect code for this rule with the 2, { "ObjectExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ObjectExpression": "first"}]*/
var foo = { bar: 1,
baz: 2 };
Examples of correct code for this rule with the 2, { "ObjectExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ObjectExpression": "first"}]*/
var foo = { bar: 1,
baz: 2 };
Compatibility
-
JSHint:
indent
- JSCS: validateIndentation Source: http://eslint.org/docs/rules/
Expected indentation of 12 spaces but found 16. Open
test: /(\.jsx|\.js)$/,
- Read upRead up
- Exclude checks
enforce consistent indentation (indent)
There are several common guidelines which require specific indentation of nested blocks and statements, like:
function hello(indentSize, type) {
if (indentSize === 4 && type !== 'tab') {
console.log('Each next indentation will increase on 4 spaces');
}
}
These are the most common scenarios recommended in different style guides:
- Two spaces, not longer and no tabs: Google, npm, Node.js, Idiomatic, Felix
- Tabs: jQuery
- Four spaces: Crockford
Rule Details
This rule enforces a consistent indentation style. The default style is 4 spaces
.
Options
This rule has a mixed option:
For example, for 2-space indentation:
{
"indent": ["error", 2]
}
Or for tabbed indentation:
{
"indent": ["error", "tab"]
}
Examples of incorrect code for this rule with the default options:
/*eslint indent: "error"*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
Examples of correct code for this rule with the default options:
/*eslint indent: "error"*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
This rule has an object option:
-
"SwitchCase"
(default: 0) enforces indentation level forcase
clauses inswitch
statements -
"VariableDeclarator"
(default: 1) enforces indentation level forvar
declarators; can also take an object to define separate rules forvar
,let
andconst
declarations. -
"outerIIFEBody"
(default: 1) enforces indentation level for file-level IIFEs. -
"MemberExpression"
(off by default) enforces indentation level for multi-line property chains (except in variable declarations and assignments) -
"FunctionDeclaration"
takes an object to define rules for function declarations.-
parameters
(off by default) enforces indentation level for parameters in a function declaration. This can either be a number indicating indentation level, or the string"first"
indicating that all parameters of the declaration must be aligned with the first parameter. -
body
(default: 1) enforces indentation level for the body of a function declaration.
-
-
"FunctionExpression"
takes an object to define rules for function expressions.-
parameters
(off by default) enforces indentation level for parameters in a function expression. This can either be a number indicating indentation level, or the string"first"
indicating that all parameters of the expression must be aligned with the first parameter. -
body
(default: 1) enforces indentation level for the body of a function expression.
-
-
"CallExpression"
takes an object to define rules for function call expressions.-
arguments
(off by default) enforces indentation level for arguments in a call expression. This can either be a number indicating indentation level, or the string"first"
indicating that all arguments of the expression must be aligned with the first argument.
-
-
"ArrayExpression"
(default: 1) enforces indentation level for elements in arrays. It can also be set to the string"first"
, indicating that all the elements in the array should be aligned with the first element. -
"ObjectExpression"
(default: 1) enforces indentation level for properties in objects. It can be set to the string"first"
, indicating that all properties in the object should be aligned with the first property.
Level of indentation denotes the multiple of the indent specified. Example:
- Indent of 4 spaces with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 8 spaces. - Indent of 2 spaces with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 4 spaces. - Indent of 2 spaces with
VariableDeclarator
set to{"var": 2, "let": 2, "const": 3}
will indent the multi-line variable declarations with 4 spaces forvar
andlet
, 6 spaces forconst
statements. - Indent of tab with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 2 tabs. - Indent of 2 spaces with
SwitchCase
set to0
will not indentcase
clauses with respect toswitch
statements. - Indent of 2 spaces with
SwitchCase
set to1
will indentcase
clauses with 2 spaces with respect toswitch
statements. - Indent of 2 spaces with
SwitchCase
set to2
will indentcase
clauses with 4 spaces with respect toswitch
statements. - Indent of tab with
SwitchCase
set to2
will indentcase
clauses with 2 tabs with respect toswitch
statements. - Indent of 2 spaces with
MemberExpression
set to0
will indent the multi-line property chains with 0 spaces. - Indent of 2 spaces with
MemberExpression
set to1
will indent the multi-line property chains with 2 spaces. - Indent of 2 spaces with
MemberExpression
set to2
will indent the multi-line property chains with 4 spaces. - Indent of 4 spaces with
MemberExpression
set to0
will indent the multi-line property chains with 0 spaces. - Indent of 4 spaces with
MemberExpression
set to1
will indent the multi-line property chains with 4 spaces. - Indent of 4 spaces with
MemberExpression
set to2
will indent the multi-line property chains with 8 spaces.
tab
Examples of incorrect code for this rule with the "tab"
option:
/*eslint indent: ["error", "tab"]*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
Examples of correct code for this rule with the "tab"
option:
/*eslint indent: ["error", "tab"]*/
if (a) {
/*tab*/b=c;
/*tab*/function foo(d) {
/*tab*//*tab*/e=f;
/*tab*/}
}
SwitchCase
Examples of incorrect code for this rule with the 2, { "SwitchCase": 1 }
options:
/*eslint indent: ["error", 2, { "SwitchCase": 1 }]*/
switch(a){
case "a":
break;
case "b":
break;
}
Examples of correct code for this rule with the 2, { "SwitchCase": 1 }
option:
/*eslint indent: ["error", 2, { "SwitchCase": 1 }]*/
switch(a){
case "a":
break;
case "b":
break;
}
VariableDeclarator
Examples of incorrect code for this rule with the 2, { "VariableDeclarator": 1 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 1 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": 1 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 1 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": 2 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 2 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": { "var": 2, "let": 2, "const": 3 } }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": { "var": 2, "let": 2, "const": 3 } }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
outerIIFEBody
Examples of incorrect code for this rule with the options 2, { "outerIIFEBody": 0 }
:
/*eslint indent: ["error", 2, { "outerIIFEBody": 0 }]*/
(function() {
function foo(x) {
return x + 1;
}
})();
if(y) {
console.log('foo');
}
Examples of correct code for this rule with the options 2, {"outerIIFEBody": 0}
:
/*eslint indent: ["error", 2, { "outerIIFEBody": 0 }]*/
(function() {
function foo(x) {
return x + 1;
}
})();
if(y) {
console.log('foo');
}
MemberExpression
Examples of incorrect code for this rule with the 2, { "MemberExpression": 1 }
options:
/*eslint indent: ["error", 2, { "MemberExpression": 1 }]*/
foo
.bar
.baz()
Examples of correct code for this rule with the 2, { "MemberExpression": 1 }
option:
/*eslint indent: ["error", 2, { "MemberExpression": 1 }]*/
foo
.bar
.baz();
// Any indentation is permitted in variable declarations and assignments.
var bip = aardvark.badger
.coyote;
FunctionDeclaration
Examples of incorrect code for this rule with the 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }]*/
function foo(bar,
baz,
qux) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }]*/
function foo(bar,
baz,
qux) {
qux();
}
Examples of incorrect code for this rule with the 2, { "FunctionDeclaration": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionDeclaration": {"parameters": "first"}}]*/
function foo(bar, baz,
qux, boop) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionDeclaration": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionDeclaration": {"parameters": "first"}}]*/
function foo(bar, baz,
qux, boop) {
qux();
}
FunctionExpression
Examples of incorrect code for this rule with the 2, { "FunctionExpression": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionExpression": {"body": 1, "parameters": 2} }]*/
var foo = function(bar,
baz,
qux) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionExpression": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionExpression": {"body": 1, "parameters": 2} }]*/
var foo = function(bar,
baz,
qux) {
qux();
}
Examples of incorrect code for this rule with the 2, { "FunctionExpression": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionExpression": {"parameters": "first"}}]*/
var foo = function(bar, baz,
qux, boop) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionExpression": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionExpression": {"parameters": "first"}}]*/
var foo = function(bar, baz,
qux, boop) {
qux();
}
CallExpression
Examples of incorrect code for this rule with the 2, { "CallExpression": {"arguments": 1} }
option:
/*eslint indent: ["error", 2, { "CallExpression": {"arguments": 1} }]*/
foo(bar,
baz,
qux
);
Examples of correct code for this rule with the 2, { "CallExpression": {"arguments": 1} }
option:
/*eslint indent: ["error", 2, { "CallExpression": {"arguments": 1} }]*/
foo(bar,
baz,
qux
);
Examples of incorrect code for this rule with the 2, { "CallExpression": {"arguments": "first"} }
option:
/*eslint indent: ["error", 2, {"CallExpression": {"arguments": "first"}}]*/
foo(bar, baz,
baz, boop, beep);
Examples of correct code for this rule with the 2, { "CallExpression": {"arguments": "first"} }
option:
/*eslint indent: ["error", 2, {"CallExpression": {"arguments": "first"}}]*/
foo(bar, baz,
baz, boop, beep);
ArrayExpression
Examples of incorrect code for this rule with the 2, { "ArrayExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ArrayExpression": 1 }]*/
var foo = [
bar,
baz,
qux
];
Examples of correct code for this rule with the 2, { "ArrayExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ArrayExpression": 1 }]*/
var foo = [
bar,
baz,
qux
];
Examples of incorrect code for this rule with the 2, { "ArrayExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ArrayExpression": "first"}]*/
var foo = [bar,
baz,
qux
];
Examples of correct code for this rule with the 2, { "ArrayExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ArrayExpression": "first"}]*/
var foo = [bar,
baz,
qux
];
ObjectExpression
Examples of incorrect code for this rule with the 2, { "ObjectExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ObjectExpression": 1 }]*/
var foo = {
bar: 1,
baz: 2,
qux: 3
};
Examples of correct code for this rule with the 2, { "ObjectExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ObjectExpression": 1 }]*/
var foo = {
bar: 1,
baz: 2,
qux: 3
};
Examples of incorrect code for this rule with the 2, { "ObjectExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ObjectExpression": "first"}]*/
var foo = { bar: 1,
baz: 2 };
Examples of correct code for this rule with the 2, { "ObjectExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ObjectExpression": "first"}]*/
var foo = { bar: 1,
baz: 2 };
Compatibility
-
JSHint:
indent
- JSCS: validateIndentation Source: http://eslint.org/docs/rules/
Expected indentation of 12 spaces but found 16. Open
exclude: /node_modules/
- Read upRead up
- Exclude checks
enforce consistent indentation (indent)
There are several common guidelines which require specific indentation of nested blocks and statements, like:
function hello(indentSize, type) {
if (indentSize === 4 && type !== 'tab') {
console.log('Each next indentation will increase on 4 spaces');
}
}
These are the most common scenarios recommended in different style guides:
- Two spaces, not longer and no tabs: Google, npm, Node.js, Idiomatic, Felix
- Tabs: jQuery
- Four spaces: Crockford
Rule Details
This rule enforces a consistent indentation style. The default style is 4 spaces
.
Options
This rule has a mixed option:
For example, for 2-space indentation:
{
"indent": ["error", 2]
}
Or for tabbed indentation:
{
"indent": ["error", "tab"]
}
Examples of incorrect code for this rule with the default options:
/*eslint indent: "error"*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
Examples of correct code for this rule with the default options:
/*eslint indent: "error"*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
This rule has an object option:
-
"SwitchCase"
(default: 0) enforces indentation level forcase
clauses inswitch
statements -
"VariableDeclarator"
(default: 1) enforces indentation level forvar
declarators; can also take an object to define separate rules forvar
,let
andconst
declarations. -
"outerIIFEBody"
(default: 1) enforces indentation level for file-level IIFEs. -
"MemberExpression"
(off by default) enforces indentation level for multi-line property chains (except in variable declarations and assignments) -
"FunctionDeclaration"
takes an object to define rules for function declarations.-
parameters
(off by default) enforces indentation level for parameters in a function declaration. This can either be a number indicating indentation level, or the string"first"
indicating that all parameters of the declaration must be aligned with the first parameter. -
body
(default: 1) enforces indentation level for the body of a function declaration.
-
-
"FunctionExpression"
takes an object to define rules for function expressions.-
parameters
(off by default) enforces indentation level for parameters in a function expression. This can either be a number indicating indentation level, or the string"first"
indicating that all parameters of the expression must be aligned with the first parameter. -
body
(default: 1) enforces indentation level for the body of a function expression.
-
-
"CallExpression"
takes an object to define rules for function call expressions.-
arguments
(off by default) enforces indentation level for arguments in a call expression. This can either be a number indicating indentation level, or the string"first"
indicating that all arguments of the expression must be aligned with the first argument.
-
-
"ArrayExpression"
(default: 1) enforces indentation level for elements in arrays. It can also be set to the string"first"
, indicating that all the elements in the array should be aligned with the first element. -
"ObjectExpression"
(default: 1) enforces indentation level for properties in objects. It can be set to the string"first"
, indicating that all properties in the object should be aligned with the first property.
Level of indentation denotes the multiple of the indent specified. Example:
- Indent of 4 spaces with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 8 spaces. - Indent of 2 spaces with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 4 spaces. - Indent of 2 spaces with
VariableDeclarator
set to{"var": 2, "let": 2, "const": 3}
will indent the multi-line variable declarations with 4 spaces forvar
andlet
, 6 spaces forconst
statements. - Indent of tab with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 2 tabs. - Indent of 2 spaces with
SwitchCase
set to0
will not indentcase
clauses with respect toswitch
statements. - Indent of 2 spaces with
SwitchCase
set to1
will indentcase
clauses with 2 spaces with respect toswitch
statements. - Indent of 2 spaces with
SwitchCase
set to2
will indentcase
clauses with 4 spaces with respect toswitch
statements. - Indent of tab with
SwitchCase
set to2
will indentcase
clauses with 2 tabs with respect toswitch
statements. - Indent of 2 spaces with
MemberExpression
set to0
will indent the multi-line property chains with 0 spaces. - Indent of 2 spaces with
MemberExpression
set to1
will indent the multi-line property chains with 2 spaces. - Indent of 2 spaces with
MemberExpression
set to2
will indent the multi-line property chains with 4 spaces. - Indent of 4 spaces with
MemberExpression
set to0
will indent the multi-line property chains with 0 spaces. - Indent of 4 spaces with
MemberExpression
set to1
will indent the multi-line property chains with 4 spaces. - Indent of 4 spaces with
MemberExpression
set to2
will indent the multi-line property chains with 8 spaces.
tab
Examples of incorrect code for this rule with the "tab"
option:
/*eslint indent: ["error", "tab"]*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
Examples of correct code for this rule with the "tab"
option:
/*eslint indent: ["error", "tab"]*/
if (a) {
/*tab*/b=c;
/*tab*/function foo(d) {
/*tab*//*tab*/e=f;
/*tab*/}
}
SwitchCase
Examples of incorrect code for this rule with the 2, { "SwitchCase": 1 }
options:
/*eslint indent: ["error", 2, { "SwitchCase": 1 }]*/
switch(a){
case "a":
break;
case "b":
break;
}
Examples of correct code for this rule with the 2, { "SwitchCase": 1 }
option:
/*eslint indent: ["error", 2, { "SwitchCase": 1 }]*/
switch(a){
case "a":
break;
case "b":
break;
}
VariableDeclarator
Examples of incorrect code for this rule with the 2, { "VariableDeclarator": 1 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 1 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": 1 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 1 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": 2 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 2 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": { "var": 2, "let": 2, "const": 3 } }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": { "var": 2, "let": 2, "const": 3 } }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
outerIIFEBody
Examples of incorrect code for this rule with the options 2, { "outerIIFEBody": 0 }
:
/*eslint indent: ["error", 2, { "outerIIFEBody": 0 }]*/
(function() {
function foo(x) {
return x + 1;
}
})();
if(y) {
console.log('foo');
}
Examples of correct code for this rule with the options 2, {"outerIIFEBody": 0}
:
/*eslint indent: ["error", 2, { "outerIIFEBody": 0 }]*/
(function() {
function foo(x) {
return x + 1;
}
})();
if(y) {
console.log('foo');
}
MemberExpression
Examples of incorrect code for this rule with the 2, { "MemberExpression": 1 }
options:
/*eslint indent: ["error", 2, { "MemberExpression": 1 }]*/
foo
.bar
.baz()
Examples of correct code for this rule with the 2, { "MemberExpression": 1 }
option:
/*eslint indent: ["error", 2, { "MemberExpression": 1 }]*/
foo
.bar
.baz();
// Any indentation is permitted in variable declarations and assignments.
var bip = aardvark.badger
.coyote;
FunctionDeclaration
Examples of incorrect code for this rule with the 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }]*/
function foo(bar,
baz,
qux) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }]*/
function foo(bar,
baz,
qux) {
qux();
}
Examples of incorrect code for this rule with the 2, { "FunctionDeclaration": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionDeclaration": {"parameters": "first"}}]*/
function foo(bar, baz,
qux, boop) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionDeclaration": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionDeclaration": {"parameters": "first"}}]*/
function foo(bar, baz,
qux, boop) {
qux();
}
FunctionExpression
Examples of incorrect code for this rule with the 2, { "FunctionExpression": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionExpression": {"body": 1, "parameters": 2} }]*/
var foo = function(bar,
baz,
qux) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionExpression": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionExpression": {"body": 1, "parameters": 2} }]*/
var foo = function(bar,
baz,
qux) {
qux();
}
Examples of incorrect code for this rule with the 2, { "FunctionExpression": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionExpression": {"parameters": "first"}}]*/
var foo = function(bar, baz,
qux, boop) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionExpression": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionExpression": {"parameters": "first"}}]*/
var foo = function(bar, baz,
qux, boop) {
qux();
}
CallExpression
Examples of incorrect code for this rule with the 2, { "CallExpression": {"arguments": 1} }
option:
/*eslint indent: ["error", 2, { "CallExpression": {"arguments": 1} }]*/
foo(bar,
baz,
qux
);
Examples of correct code for this rule with the 2, { "CallExpression": {"arguments": 1} }
option:
/*eslint indent: ["error", 2, { "CallExpression": {"arguments": 1} }]*/
foo(bar,
baz,
qux
);
Examples of incorrect code for this rule with the 2, { "CallExpression": {"arguments": "first"} }
option:
/*eslint indent: ["error", 2, {"CallExpression": {"arguments": "first"}}]*/
foo(bar, baz,
baz, boop, beep);
Examples of correct code for this rule with the 2, { "CallExpression": {"arguments": "first"} }
option:
/*eslint indent: ["error", 2, {"CallExpression": {"arguments": "first"}}]*/
foo(bar, baz,
baz, boop, beep);
ArrayExpression
Examples of incorrect code for this rule with the 2, { "ArrayExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ArrayExpression": 1 }]*/
var foo = [
bar,
baz,
qux
];
Examples of correct code for this rule with the 2, { "ArrayExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ArrayExpression": 1 }]*/
var foo = [
bar,
baz,
qux
];
Examples of incorrect code for this rule with the 2, { "ArrayExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ArrayExpression": "first"}]*/
var foo = [bar,
baz,
qux
];
Examples of correct code for this rule with the 2, { "ArrayExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ArrayExpression": "first"}]*/
var foo = [bar,
baz,
qux
];
ObjectExpression
Examples of incorrect code for this rule with the 2, { "ObjectExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ObjectExpression": 1 }]*/
var foo = {
bar: 1,
baz: 2,
qux: 3
};
Examples of correct code for this rule with the 2, { "ObjectExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ObjectExpression": 1 }]*/
var foo = {
bar: 1,
baz: 2,
qux: 3
};
Examples of incorrect code for this rule with the 2, { "ObjectExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ObjectExpression": "first"}]*/
var foo = { bar: 1,
baz: 2 };
Examples of correct code for this rule with the 2, { "ObjectExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ObjectExpression": "first"}]*/
var foo = { bar: 1,
baz: 2 };
Compatibility
-
JSHint:
indent
- JSCS: validateIndentation Source: http://eslint.org/docs/rules/
Unexpected console statement. Open
console.log('Use ' + chalk.yellow('// eslint-disable-next-line') + ' to ignore the next line.');
- Read upRead up
- Exclude checks
disallow the use of console
(no-console)
In JavaScript that is designed to be executed in the browser, it's considered a best practice to avoid using methods on console
. Such messages are considered to be for debugging purposes and therefore not suitable to ship to the client. In general, calls using console
should be stripped before being pushed to production.
console.log("Made it here.");
console.error("That shouldn't have happened.");
Rule Details
This rule disallows calls to methods of the console
object.
Examples of incorrect code for this rule:
/*eslint no-console: "error"*/
console.log("Log a debug level message.");
console.warn("Log a warn level message.");
console.error("Log an error level message.");
Examples of correct code for this rule:
/*eslint no-console: "error"*/
// custom console
Console.log("Hello world!");
Options
This rule has an object option for exceptions:
-
"allow"
has an array of strings which are allowed methods of theconsole
object
Examples of additional correct code for this rule with a sample { "allow": ["warn", "error"] }
option:
/*eslint no-console: ["error", { allow: ["warn", "error"] }] */
console.warn("Log a warn level message.");
console.error("Log an error level message.");
When Not To Use It
If you're using Node.js, however, console
is used to output information to the user and so is not strictly used for debugging purposes. If you are developing for Node.js then you most likely do not want this rule enabled.
Related Rules
- [no-alert](no-alert.md)
- [no-debugger](no-debugger.md) Source: http://eslint.org/docs/rules/
Unexpected string concatenation. Open
chalk.yellow('Something is already running on port ' + DEFAULT_PORT + '.' +
- Read upRead up
- Exclude checks
Suggest using template literals instead of string concatenation. (prefer-template)
In ES2015 (ES6), we can use template literals instead of string concatenation.
var str = "Hello, " + name + "!";
/*eslint-env es6*/
var str = `Hello, ${name}!`;
Rule Details
This rule is aimed to flag usage of +
operators with strings.
Examples
Examples of incorrect code for this rule:
/*eslint prefer-template: "error"*/
var str = "Hello, " + name + "!";
var str = "Time: " + (12 * 60 * 60 * 1000);
Examples of correct code for this rule:
/*eslint prefer-template: "error"*/
/*eslint-env es6*/
var str = "Hello World!";
var str = `Hello, ${name}!`;
var str = `Time: ${12 * 60 * 60 * 1000}`;
// This is reported by `no-useless-concat`.
var str = "Hello, " + "World!";
When Not To Use It
This rule should not be used in ES3/5 environments.
In ES2015 (ES6) or later, if you don't want to be notified about string concatenation, you can safely disable this rule.
Related Rules
- [no-useless-concat](no-useless-concat.md)
- [quotes](quotes.md) Source: http://eslint.org/docs/rules/
Expected indentation of 6 spaces but found 8. Open
filename: outputFile,
- Read upRead up
- Exclude checks
enforce consistent indentation (indent)
There are several common guidelines which require specific indentation of nested blocks and statements, like:
function hello(indentSize, type) {
if (indentSize === 4 && type !== 'tab') {
console.log('Each next indentation will increase on 4 spaces');
}
}
These are the most common scenarios recommended in different style guides:
- Two spaces, not longer and no tabs: Google, npm, Node.js, Idiomatic, Felix
- Tabs: jQuery
- Four spaces: Crockford
Rule Details
This rule enforces a consistent indentation style. The default style is 4 spaces
.
Options
This rule has a mixed option:
For example, for 2-space indentation:
{
"indent": ["error", 2]
}
Or for tabbed indentation:
{
"indent": ["error", "tab"]
}
Examples of incorrect code for this rule with the default options:
/*eslint indent: "error"*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
Examples of correct code for this rule with the default options:
/*eslint indent: "error"*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
This rule has an object option:
-
"SwitchCase"
(default: 0) enforces indentation level forcase
clauses inswitch
statements -
"VariableDeclarator"
(default: 1) enforces indentation level forvar
declarators; can also take an object to define separate rules forvar
,let
andconst
declarations. -
"outerIIFEBody"
(default: 1) enforces indentation level for file-level IIFEs. -
"MemberExpression"
(off by default) enforces indentation level for multi-line property chains (except in variable declarations and assignments) -
"FunctionDeclaration"
takes an object to define rules for function declarations.-
parameters
(off by default) enforces indentation level for parameters in a function declaration. This can either be a number indicating indentation level, or the string"first"
indicating that all parameters of the declaration must be aligned with the first parameter. -
body
(default: 1) enforces indentation level for the body of a function declaration.
-
-
"FunctionExpression"
takes an object to define rules for function expressions.-
parameters
(off by default) enforces indentation level for parameters in a function expression. This can either be a number indicating indentation level, or the string"first"
indicating that all parameters of the expression must be aligned with the first parameter. -
body
(default: 1) enforces indentation level for the body of a function expression.
-
-
"CallExpression"
takes an object to define rules for function call expressions.-
arguments
(off by default) enforces indentation level for arguments in a call expression. This can either be a number indicating indentation level, or the string"first"
indicating that all arguments of the expression must be aligned with the first argument.
-
-
"ArrayExpression"
(default: 1) enforces indentation level for elements in arrays. It can also be set to the string"first"
, indicating that all the elements in the array should be aligned with the first element. -
"ObjectExpression"
(default: 1) enforces indentation level for properties in objects. It can be set to the string"first"
, indicating that all properties in the object should be aligned with the first property.
Level of indentation denotes the multiple of the indent specified. Example:
- Indent of 4 spaces with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 8 spaces. - Indent of 2 spaces with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 4 spaces. - Indent of 2 spaces with
VariableDeclarator
set to{"var": 2, "let": 2, "const": 3}
will indent the multi-line variable declarations with 4 spaces forvar
andlet
, 6 spaces forconst
statements. - Indent of tab with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 2 tabs. - Indent of 2 spaces with
SwitchCase
set to0
will not indentcase
clauses with respect toswitch
statements. - Indent of 2 spaces with
SwitchCase
set to1
will indentcase
clauses with 2 spaces with respect toswitch
statements. - Indent of 2 spaces with
SwitchCase
set to2
will indentcase
clauses with 4 spaces with respect toswitch
statements. - Indent of tab with
SwitchCase
set to2
will indentcase
clauses with 2 tabs with respect toswitch
statements. - Indent of 2 spaces with
MemberExpression
set to0
will indent the multi-line property chains with 0 spaces. - Indent of 2 spaces with
MemberExpression
set to1
will indent the multi-line property chains with 2 spaces. - Indent of 2 spaces with
MemberExpression
set to2
will indent the multi-line property chains with 4 spaces. - Indent of 4 spaces with
MemberExpression
set to0
will indent the multi-line property chains with 0 spaces. - Indent of 4 spaces with
MemberExpression
set to1
will indent the multi-line property chains with 4 spaces. - Indent of 4 spaces with
MemberExpression
set to2
will indent the multi-line property chains with 8 spaces.
tab
Examples of incorrect code for this rule with the "tab"
option:
/*eslint indent: ["error", "tab"]*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
Examples of correct code for this rule with the "tab"
option:
/*eslint indent: ["error", "tab"]*/
if (a) {
/*tab*/b=c;
/*tab*/function foo(d) {
/*tab*//*tab*/e=f;
/*tab*/}
}
SwitchCase
Examples of incorrect code for this rule with the 2, { "SwitchCase": 1 }
options:
/*eslint indent: ["error", 2, { "SwitchCase": 1 }]*/
switch(a){
case "a":
break;
case "b":
break;
}
Examples of correct code for this rule with the 2, { "SwitchCase": 1 }
option:
/*eslint indent: ["error", 2, { "SwitchCase": 1 }]*/
switch(a){
case "a":
break;
case "b":
break;
}
VariableDeclarator
Examples of incorrect code for this rule with the 2, { "VariableDeclarator": 1 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 1 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": 1 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 1 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": 2 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 2 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": { "var": 2, "let": 2, "const": 3 } }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": { "var": 2, "let": 2, "const": 3 } }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
outerIIFEBody
Examples of incorrect code for this rule with the options 2, { "outerIIFEBody": 0 }
:
/*eslint indent: ["error", 2, { "outerIIFEBody": 0 }]*/
(function() {
function foo(x) {
return x + 1;
}
})();
if(y) {
console.log('foo');
}
Examples of correct code for this rule with the options 2, {"outerIIFEBody": 0}
:
/*eslint indent: ["error", 2, { "outerIIFEBody": 0 }]*/
(function() {
function foo(x) {
return x + 1;
}
})();
if(y) {
console.log('foo');
}
MemberExpression
Examples of incorrect code for this rule with the 2, { "MemberExpression": 1 }
options:
/*eslint indent: ["error", 2, { "MemberExpression": 1 }]*/
foo
.bar
.baz()
Examples of correct code for this rule with the 2, { "MemberExpression": 1 }
option:
/*eslint indent: ["error", 2, { "MemberExpression": 1 }]*/
foo
.bar
.baz();
// Any indentation is permitted in variable declarations and assignments.
var bip = aardvark.badger
.coyote;
FunctionDeclaration
Examples of incorrect code for this rule with the 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }]*/
function foo(bar,
baz,
qux) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }]*/
function foo(bar,
baz,
qux) {
qux();
}
Examples of incorrect code for this rule with the 2, { "FunctionDeclaration": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionDeclaration": {"parameters": "first"}}]*/
function foo(bar, baz,
qux, boop) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionDeclaration": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionDeclaration": {"parameters": "first"}}]*/
function foo(bar, baz,
qux, boop) {
qux();
}
FunctionExpression
Examples of incorrect code for this rule with the 2, { "FunctionExpression": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionExpression": {"body": 1, "parameters": 2} }]*/
var foo = function(bar,
baz,
qux) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionExpression": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionExpression": {"body": 1, "parameters": 2} }]*/
var foo = function(bar,
baz,
qux) {
qux();
}
Examples of incorrect code for this rule with the 2, { "FunctionExpression": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionExpression": {"parameters": "first"}}]*/
var foo = function(bar, baz,
qux, boop) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionExpression": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionExpression": {"parameters": "first"}}]*/
var foo = function(bar, baz,
qux, boop) {
qux();
}
CallExpression
Examples of incorrect code for this rule with the 2, { "CallExpression": {"arguments": 1} }
option:
/*eslint indent: ["error", 2, { "CallExpression": {"arguments": 1} }]*/
foo(bar,
baz,
qux
);
Examples of correct code for this rule with the 2, { "CallExpression": {"arguments": 1} }
option:
/*eslint indent: ["error", 2, { "CallExpression": {"arguments": 1} }]*/
foo(bar,
baz,
qux
);
Examples of incorrect code for this rule with the 2, { "CallExpression": {"arguments": "first"} }
option:
/*eslint indent: ["error", 2, {"CallExpression": {"arguments": "first"}}]*/
foo(bar, baz,
baz, boop, beep);
Examples of correct code for this rule with the 2, { "CallExpression": {"arguments": "first"} }
option:
/*eslint indent: ["error", 2, {"CallExpression": {"arguments": "first"}}]*/
foo(bar, baz,
baz, boop, beep);
ArrayExpression
Examples of incorrect code for this rule with the 2, { "ArrayExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ArrayExpression": 1 }]*/
var foo = [
bar,
baz,
qux
];
Examples of correct code for this rule with the 2, { "ArrayExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ArrayExpression": 1 }]*/
var foo = [
bar,
baz,
qux
];
Examples of incorrect code for this rule with the 2, { "ArrayExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ArrayExpression": "first"}]*/
var foo = [bar,
baz,
qux
];
Examples of correct code for this rule with the 2, { "ArrayExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ArrayExpression": "first"}]*/
var foo = [bar,
baz,
qux
];
ObjectExpression
Examples of incorrect code for this rule with the 2, { "ObjectExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ObjectExpression": 1 }]*/
var foo = {
bar: 1,
baz: 2,
qux: 3
};
Examples of correct code for this rule with the 2, { "ObjectExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ObjectExpression": 1 }]*/
var foo = {
bar: 1,
baz: 2,
qux: 3
};
Examples of incorrect code for this rule with the 2, { "ObjectExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ObjectExpression": "first"}]*/
var foo = { bar: 1,
baz: 2 };
Examples of correct code for this rule with the 2, { "ObjectExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ObjectExpression": "first"}]*/
var foo = { bar: 1,
baz: 2 };
Compatibility
-
JSHint:
indent
- JSCS: validateIndentation Source: http://eslint.org/docs/rules/
Expected indentation of 2 spaces but found 4. Open
plugins: plugins
- Read upRead up
- Exclude checks
enforce consistent indentation (indent)
There are several common guidelines which require specific indentation of nested blocks and statements, like:
function hello(indentSize, type) {
if (indentSize === 4 && type !== 'tab') {
console.log('Each next indentation will increase on 4 spaces');
}
}
These are the most common scenarios recommended in different style guides:
- Two spaces, not longer and no tabs: Google, npm, Node.js, Idiomatic, Felix
- Tabs: jQuery
- Four spaces: Crockford
Rule Details
This rule enforces a consistent indentation style. The default style is 4 spaces
.
Options
This rule has a mixed option:
For example, for 2-space indentation:
{
"indent": ["error", 2]
}
Or for tabbed indentation:
{
"indent": ["error", "tab"]
}
Examples of incorrect code for this rule with the default options:
/*eslint indent: "error"*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
Examples of correct code for this rule with the default options:
/*eslint indent: "error"*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
This rule has an object option:
-
"SwitchCase"
(default: 0) enforces indentation level forcase
clauses inswitch
statements -
"VariableDeclarator"
(default: 1) enforces indentation level forvar
declarators; can also take an object to define separate rules forvar
,let
andconst
declarations. -
"outerIIFEBody"
(default: 1) enforces indentation level for file-level IIFEs. -
"MemberExpression"
(off by default) enforces indentation level for multi-line property chains (except in variable declarations and assignments) -
"FunctionDeclaration"
takes an object to define rules for function declarations.-
parameters
(off by default) enforces indentation level for parameters in a function declaration. This can either be a number indicating indentation level, or the string"first"
indicating that all parameters of the declaration must be aligned with the first parameter. -
body
(default: 1) enforces indentation level for the body of a function declaration.
-
-
"FunctionExpression"
takes an object to define rules for function expressions.-
parameters
(off by default) enforces indentation level for parameters in a function expression. This can either be a number indicating indentation level, or the string"first"
indicating that all parameters of the expression must be aligned with the first parameter. -
body
(default: 1) enforces indentation level for the body of a function expression.
-
-
"CallExpression"
takes an object to define rules for function call expressions.-
arguments
(off by default) enforces indentation level for arguments in a call expression. This can either be a number indicating indentation level, or the string"first"
indicating that all arguments of the expression must be aligned with the first argument.
-
-
"ArrayExpression"
(default: 1) enforces indentation level for elements in arrays. It can also be set to the string"first"
, indicating that all the elements in the array should be aligned with the first element. -
"ObjectExpression"
(default: 1) enforces indentation level for properties in objects. It can be set to the string"first"
, indicating that all properties in the object should be aligned with the first property.
Level of indentation denotes the multiple of the indent specified. Example:
- Indent of 4 spaces with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 8 spaces. - Indent of 2 spaces with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 4 spaces. - Indent of 2 spaces with
VariableDeclarator
set to{"var": 2, "let": 2, "const": 3}
will indent the multi-line variable declarations with 4 spaces forvar
andlet
, 6 spaces forconst
statements. - Indent of tab with
VariableDeclarator
set to2
will indent the multi-line variable declarations with 2 tabs. - Indent of 2 spaces with
SwitchCase
set to0
will not indentcase
clauses with respect toswitch
statements. - Indent of 2 spaces with
SwitchCase
set to1
will indentcase
clauses with 2 spaces with respect toswitch
statements. - Indent of 2 spaces with
SwitchCase
set to2
will indentcase
clauses with 4 spaces with respect toswitch
statements. - Indent of tab with
SwitchCase
set to2
will indentcase
clauses with 2 tabs with respect toswitch
statements. - Indent of 2 spaces with
MemberExpression
set to0
will indent the multi-line property chains with 0 spaces. - Indent of 2 spaces with
MemberExpression
set to1
will indent the multi-line property chains with 2 spaces. - Indent of 2 spaces with
MemberExpression
set to2
will indent the multi-line property chains with 4 spaces. - Indent of 4 spaces with
MemberExpression
set to0
will indent the multi-line property chains with 0 spaces. - Indent of 4 spaces with
MemberExpression
set to1
will indent the multi-line property chains with 4 spaces. - Indent of 4 spaces with
MemberExpression
set to2
will indent the multi-line property chains with 8 spaces.
tab
Examples of incorrect code for this rule with the "tab"
option:
/*eslint indent: ["error", "tab"]*/
if (a) {
b=c;
function foo(d) {
e=f;
}
}
Examples of correct code for this rule with the "tab"
option:
/*eslint indent: ["error", "tab"]*/
if (a) {
/*tab*/b=c;
/*tab*/function foo(d) {
/*tab*//*tab*/e=f;
/*tab*/}
}
SwitchCase
Examples of incorrect code for this rule with the 2, { "SwitchCase": 1 }
options:
/*eslint indent: ["error", 2, { "SwitchCase": 1 }]*/
switch(a){
case "a":
break;
case "b":
break;
}
Examples of correct code for this rule with the 2, { "SwitchCase": 1 }
option:
/*eslint indent: ["error", 2, { "SwitchCase": 1 }]*/
switch(a){
case "a":
break;
case "b":
break;
}
VariableDeclarator
Examples of incorrect code for this rule with the 2, { "VariableDeclarator": 1 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 1 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": 1 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 1 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": 2 }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": 2 }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
Examples of correct code for this rule with the 2, { "VariableDeclarator": { "var": 2, "let": 2, "const": 3 } }
options:
/*eslint indent: ["error", 2, { "VariableDeclarator": { "var": 2, "let": 2, "const": 3 } }]*/
/*eslint-env es6*/
var a,
b,
c;
let a,
b,
c;
const a = 1,
b = 2,
c = 3;
outerIIFEBody
Examples of incorrect code for this rule with the options 2, { "outerIIFEBody": 0 }
:
/*eslint indent: ["error", 2, { "outerIIFEBody": 0 }]*/
(function() {
function foo(x) {
return x + 1;
}
})();
if(y) {
console.log('foo');
}
Examples of correct code for this rule with the options 2, {"outerIIFEBody": 0}
:
/*eslint indent: ["error", 2, { "outerIIFEBody": 0 }]*/
(function() {
function foo(x) {
return x + 1;
}
})();
if(y) {
console.log('foo');
}
MemberExpression
Examples of incorrect code for this rule with the 2, { "MemberExpression": 1 }
options:
/*eslint indent: ["error", 2, { "MemberExpression": 1 }]*/
foo
.bar
.baz()
Examples of correct code for this rule with the 2, { "MemberExpression": 1 }
option:
/*eslint indent: ["error", 2, { "MemberExpression": 1 }]*/
foo
.bar
.baz();
// Any indentation is permitted in variable declarations and assignments.
var bip = aardvark.badger
.coyote;
FunctionDeclaration
Examples of incorrect code for this rule with the 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }]*/
function foo(bar,
baz,
qux) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionDeclaration": {"body": 1, "parameters": 2} }]*/
function foo(bar,
baz,
qux) {
qux();
}
Examples of incorrect code for this rule with the 2, { "FunctionDeclaration": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionDeclaration": {"parameters": "first"}}]*/
function foo(bar, baz,
qux, boop) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionDeclaration": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionDeclaration": {"parameters": "first"}}]*/
function foo(bar, baz,
qux, boop) {
qux();
}
FunctionExpression
Examples of incorrect code for this rule with the 2, { "FunctionExpression": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionExpression": {"body": 1, "parameters": 2} }]*/
var foo = function(bar,
baz,
qux) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionExpression": {"body": 1, "parameters": 2} }
option:
/*eslint indent: ["error", 2, { "FunctionExpression": {"body": 1, "parameters": 2} }]*/
var foo = function(bar,
baz,
qux) {
qux();
}
Examples of incorrect code for this rule with the 2, { "FunctionExpression": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionExpression": {"parameters": "first"}}]*/
var foo = function(bar, baz,
qux, boop) {
qux();
}
Examples of correct code for this rule with the 2, { "FunctionExpression": {"parameters": "first"} }
option:
/*eslint indent: ["error", 2, {"FunctionExpression": {"parameters": "first"}}]*/
var foo = function(bar, baz,
qux, boop) {
qux();
}
CallExpression
Examples of incorrect code for this rule with the 2, { "CallExpression": {"arguments": 1} }
option:
/*eslint indent: ["error", 2, { "CallExpression": {"arguments": 1} }]*/
foo(bar,
baz,
qux
);
Examples of correct code for this rule with the 2, { "CallExpression": {"arguments": 1} }
option:
/*eslint indent: ["error", 2, { "CallExpression": {"arguments": 1} }]*/
foo(bar,
baz,
qux
);
Examples of incorrect code for this rule with the 2, { "CallExpression": {"arguments": "first"} }
option:
/*eslint indent: ["error", 2, {"CallExpression": {"arguments": "first"}}]*/
foo(bar, baz,
baz, boop, beep);
Examples of correct code for this rule with the 2, { "CallExpression": {"arguments": "first"} }
option:
/*eslint indent: ["error", 2, {"CallExpression": {"arguments": "first"}}]*/
foo(bar, baz,
baz, boop, beep);
ArrayExpression
Examples of incorrect code for this rule with the 2, { "ArrayExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ArrayExpression": 1 }]*/
var foo = [
bar,
baz,
qux
];
Examples of correct code for this rule with the 2, { "ArrayExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ArrayExpression": 1 }]*/
var foo = [
bar,
baz,
qux
];
Examples of incorrect code for this rule with the 2, { "ArrayExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ArrayExpression": "first"}]*/
var foo = [bar,
baz,
qux
];
Examples of correct code for this rule with the 2, { "ArrayExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ArrayExpression": "first"}]*/
var foo = [bar,
baz,
qux
];
ObjectExpression
Examples of incorrect code for this rule with the 2, { "ObjectExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ObjectExpression": 1 }]*/
var foo = {
bar: 1,
baz: 2,
qux: 3
};
Examples of correct code for this rule with the 2, { "ObjectExpression": 1 }
option:
/*eslint indent: ["error", 2, { "ObjectExpression": 1 }]*/
var foo = {
bar: 1,
baz: 2,
qux: 3
};
Examples of incorrect code for this rule with the 2, { "ObjectExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ObjectExpression": "first"}]*/
var foo = { bar: 1,
baz: 2 };
Examples of correct code for this rule with the 2, { "ObjectExpression": "first" }
option:
/*eslint indent: ["error", 2, {"ObjectExpression": "first"}]*/
var foo = { bar: 1,
baz: 2 };
Compatibility
-
JSHint:
indent
- JSCS: validateIndentation Source: http://eslint.org/docs/rules/
Missing trailing comma. Open
plugins: plugins
- Read upRead up
- Exclude checks
require or disallow trailing commas (comma-dangle)
Trailing commas in object literals are valid according to the ECMAScript 5 (and ECMAScript 3!) spec. However, IE8 (when not in IE8 document mode) and below will throw an error when it encounters trailing commas in JavaScript.
var foo = {
bar: "baz",
qux: "quux",
};
Trailing commas simplify adding and removing items to objects and arrays, since only the lines you are modifying must be touched. Another argument in favor of trailing commas is that it improves the clarity of diffs when an item is added or removed from an object or array:
Less clear:
var foo = {
- bar: "baz",
- qux: "quux"
+ bar: "baz"
};
More clear:
var foo = {
bar: "baz",
- qux: "quux",
};
Rule Details
This rule enforces consistent use of trailing commas in object and array literals.
Options
This rule has a string option or an object option:
{
"comma-dangle": ["error", "never"],
// or
"comma-dangle": ["error", {
"arrays": "never",
"objects": "never",
"imports": "never",
"exports": "never",
"functions": "ignore",
}]
}
-
"never"
(default) disallows trailing commas -
"always"
requires trailing commas -
"always-multiline"
requires trailing commas when the last element or property is in a different line than the closing]
or}
and disallows trailing commas when the last element or property is on the same line as the closing]
or}
-
"only-multiline"
allows (but does not require) trailing commas when the last element or property is in a different line than the closing]
or}
and disallows trailing commas when the last element or property is on the same line as the closing]
or}
Trailing commas in function declarations and function calls are valid syntax since ECMAScript 2017; however, the string option does not check these situations for backwards compatibility.
You can also use an object option to configure this rule for each type of syntax.
Each of the following options can be set to "never"
, "always"
, "always-multiline"
, "only-multiline"
, or "ignore"
.
The default for each option is "never"
unless otherwise specified.
-
arrays
is for array literals and array patterns of destructuring. (e.g.let [a,] = [1,];
) -
objects
is for object literals and object patterns of destructuring. (e.g.let {a,} = {a: 1};
) -
imports
is for import declarations of ES Modules. (e.g.import {a,} from "foo";
) -
exports
is for export declarations of ES Modules. (e.g.export {a,};
) -
functions
is for function declarations and function calls. (e.g.(function(a,){ })(b,);
)
functions
is set to"ignore"
by default for consistency with the string option.
never
Examples of incorrect code for this rule with the default "never"
option:
/*eslint comma-dangle: ["error", "never"]*/
var foo = {
bar: "baz",
qux: "quux",
};
var arr = [1,2,];
foo({
bar: "baz",
qux: "quux",
});
Examples of correct code for this rule with the default "never"
option:
/*eslint comma-dangle: ["error", "never"]*/
var foo = {
bar: "baz",
qux: "quux"
};
var arr = [1,2];
foo({
bar: "baz",
qux: "quux"
});
always
Examples of incorrect code for this rule with the "always"
option:
/*eslint comma-dangle: ["error", "always"]*/
var foo = {
bar: "baz",
qux: "quux"
};
var arr = [1,2];
foo({
bar: "baz",
qux: "quux"
});
Examples of correct code for this rule with the "always"
option:
/*eslint comma-dangle: ["error", "always"]*/
var foo = {
bar: "baz",
qux: "quux",
};
var arr = [1,2,];
foo({
bar: "baz",
qux: "quux",
});
always-multiline
Examples of incorrect code for this rule with the "always-multiline"
option:
/*eslint comma-dangle: ["error", "always-multiline"]*/
var foo = {
bar: "baz",
qux: "quux"
};
var foo = { bar: "baz", qux: "quux", };
var arr = [1,2,];
var arr = [1,
2,];
var arr = [
1,
2
];
foo({
bar: "baz",
qux: "quux"
});
Examples of correct code for this rule with the "always-multiline"
option:
/*eslint comma-dangle: ["error", "always-multiline"]*/
var foo = {
bar: "baz",
qux: "quux",
};
var foo = {bar: "baz", qux: "quux"};
var arr = [1,2];
var arr = [1,
2];
var arr = [
1,
2,
];
foo({
bar: "baz",
qux: "quux",
});
only-multiline
Examples of incorrect code for this rule with the "only-multiline"
option:
/*eslint comma-dangle: ["error", "only-multiline"]*/
var foo = { bar: "baz", qux: "quux", };
var arr = [1,2,];
var arr = [1,
2,];
Examples of correct code for this rule with the "only-multiline"
option:
/*eslint comma-dangle: ["error", "only-multiline"]*/
var foo = {
bar: "baz",
qux: "quux",
};
var foo = {
bar: "baz",
qux: "quux"
};
var foo = {bar: "baz", qux: "quux"};
var arr = [1,2];
var arr = [1,
2];
var arr = [
1,
2,
];
var arr = [
1,
2
];
foo({
bar: "baz",
qux: "quux",
});
foo({
bar: "baz",
qux: "quux"
});
functions
Examples of incorrect code for this rule with the {"functions": "never"}
option:
/*eslint comma-dangle: ["error", {"functions": "never"}]*/
function foo(a, b,) {
}
foo(a, b,);
new foo(a, b,);
Examples of correct code for this rule with the {"functions": "never"}
option:
/*eslint comma-dangle: ["error", {"functions": "never"}]*/
function foo(a, b) {
}
foo(a, b);
new foo(a, b);
Examples of incorrect code for this rule with the {"functions": "always"}
option:
/*eslint comma-dangle: ["error", {"functions": "always"}]*/
function foo(a, b) {
}
foo(a, b);
new foo(a, b);
Examples of correct code for this rule with the {"functions": "always"}
option:
/*eslint comma-dangle: ["error", {"functions": "always"}]*/
function foo(a, b,) {
}
foo(a, b,);
new foo(a, b,);
When Not To Use It
You can turn this rule off if you are not concerned with dangling commas. Source: http://eslint.org/docs/rules/
Unexpected console statement. Open
console.log();
- Read upRead up
- Exclude checks
disallow the use of console
(no-console)
In JavaScript that is designed to be executed in the browser, it's considered a best practice to avoid using methods on console
. Such messages are considered to be for debugging purposes and therefore not suitable to ship to the client. In general, calls using console
should be stripped before being pushed to production.
console.log("Made it here.");
console.error("That shouldn't have happened.");
Rule Details
This rule disallows calls to methods of the console
object.
Examples of incorrect code for this rule:
/*eslint no-console: "error"*/
console.log("Log a debug level message.");
console.warn("Log a warn level message.");
console.error("Log an error level message.");
Examples of correct code for this rule:
/*eslint no-console: "error"*/
// custom console
Console.log("Hello world!");
Options
This rule has an object option for exceptions:
-
"allow"
has an array of strings which are allowed methods of theconsole
object
Examples of additional correct code for this rule with a sample { "allow": ["warn", "error"] }
option:
/*eslint no-console: ["error", { allow: ["warn", "error"] }] */
console.warn("Log a warn level message.");
console.error("Log an error level message.");
When Not To Use It
If you're using Node.js, however, console
is used to output information to the user and so is not strictly used for debugging purposes. If you are developing for Node.js then you most likely do not want this rule enabled.
Related Rules
- [no-alert](no-alert.md)
- [no-debugger](no-debugger.md) Source: http://eslint.org/docs/rules/
Missing trailing comma. Open
' from ' + chalk.cyan(host) + ' to ' + chalk.cyan(proxy) + '.'
- Read upRead up
- Exclude checks
require or disallow trailing commas (comma-dangle)
Trailing commas in object literals are valid according to the ECMAScript 5 (and ECMAScript 3!) spec. However, IE8 (when not in IE8 document mode) and below will throw an error when it encounters trailing commas in JavaScript.
var foo = {
bar: "baz",
qux: "quux",
};
Trailing commas simplify adding and removing items to objects and arrays, since only the lines you are modifying must be touched. Another argument in favor of trailing commas is that it improves the clarity of diffs when an item is added or removed from an object or array:
Less clear:
var foo = {
- bar: "baz",
- qux: "quux"
+ bar: "baz"
};
More clear:
var foo = {
bar: "baz",
- qux: "quux",
};
Rule Details
This rule enforces consistent use of trailing commas in object and array literals.
Options
This rule has a string option or an object option:
{
"comma-dangle": ["error", "never"],
// or
"comma-dangle": ["error", {
"arrays": "never",
"objects": "never",
"imports": "never",
"exports": "never",
"functions": "ignore",
}]
}
-
"never"
(default) disallows trailing commas -
"always"
requires trailing commas -
"always-multiline"
requires trailing commas when the last element or property is in a different line than the closing]
or}
and disallows trailing commas when the last element or property is on the same line as the closing]
or}
-
"only-multiline"
allows (but does not require) trailing commas when the last element or property is in a different line than the closing]
or}
and disallows trailing commas when the last element or property is on the same line as the closing]
or}
Trailing commas in function declarations and function calls are valid syntax since ECMAScript 2017; however, the string option does not check these situations for backwards compatibility.
You can also use an object option to configure this rule for each type of syntax.
Each of the following options can be set to "never"
, "always"
, "always-multiline"
, "only-multiline"
, or "ignore"
.
The default for each option is "never"
unless otherwise specified.
-
arrays
is for array literals and array patterns of destructuring. (e.g.let [a,] = [1,];
) -
objects
is for object literals and object patterns of destructuring. (e.g.let {a,} = {a: 1};
) -
imports
is for import declarations of ES Modules. (e.g.import {a,} from "foo";
) -
exports
is for export declarations of ES Modules. (e.g.export {a,};
) -
functions
is for function declarations and function calls. (e.g.(function(a,){ })(b,);
)
functions
is set to"ignore"
by default for consistency with the string option.
never
Examples of incorrect code for this rule with the default "never"
option:
/*eslint comma-dangle: ["error", "never"]*/
var foo = {
bar: "baz",
qux: "quux",
};
var arr = [1,2,];
foo({
bar: "baz",
qux: "quux",
});
Examples of correct code for this rule with the default "never"
option:
/*eslint comma-dangle: ["error", "never"]*/
var foo = {
bar: "baz",
qux: "quux"
};
var arr = [1,2];
foo({
bar: "baz",
qux: "quux"
});
always
Examples of incorrect code for this rule with the "always"
option:
/*eslint comma-dangle: ["error", "always"]*/
var foo = {
bar: "baz",
qux: "quux"
};
var arr = [1,2];
foo({
bar: "baz",
qux: "quux"
});
Examples of correct code for this rule with the "always"
option:
/*eslint comma-dangle: ["error", "always"]*/
var foo = {
bar: "baz",
qux: "quux",
};
var arr = [1,2,];
foo({
bar: "baz",
qux: "quux",
});
always-multiline
Examples of incorrect code for this rule with the "always-multiline"
option:
/*eslint comma-dangle: ["error", "always-multiline"]*/
var foo = {
bar: "baz",
qux: "quux"
};
var foo = { bar: "baz", qux: "quux", };
var arr = [1,2,];
var arr = [1,
2,];
var arr = [
1,
2
];
foo({
bar: "baz",
qux: "quux"
});
Examples of correct code for this rule with the "always-multiline"
option:
/*eslint comma-dangle: ["error", "always-multiline"]*/
var foo = {
bar: "baz",
qux: "quux",
};
var foo = {bar: "baz", qux: "quux"};
var arr = [1,2];
var arr = [1,
2];
var arr = [
1,
2,
];
foo({
bar: "baz",
qux: "quux",
});
only-multiline
Examples of incorrect code for this rule with the "only-multiline"
option:
/*eslint comma-dangle: ["error", "only-multiline"]*/
var foo = { bar: "baz", qux: "quux", };
var arr = [1,2,];
var arr = [1,
2,];
Examples of correct code for this rule with the "only-multiline"
option:
/*eslint comma-dangle: ["error", "only-multiline"]*/
var foo = {
bar: "baz",
qux: "quux",
};
var foo = {
bar: "baz",
qux: "quux"
};
var foo = {bar: "baz", qux: "quux"};
var arr = [1,2];
var arr = [1,
2];
var arr = [
1,
2,
];
var arr = [
1,
2
];
foo({
bar: "baz",
qux: "quux",
});
foo({
bar: "baz",
qux: "quux"
});
functions
Examples of incorrect code for this rule with the {"functions": "never"}
option:
/*eslint comma-dangle: ["error", {"functions": "never"}]*/
function foo(a, b,) {
}
foo(a, b,);
new foo(a, b,);
Examples of correct code for this rule with the {"functions": "never"}
option:
/*eslint comma-dangle: ["error", {"functions": "never"}]*/
function foo(a, b) {
}
foo(a, b);
new foo(a, b);
Examples of incorrect code for this rule with the {"functions": "always"}
option:
/*eslint comma-dangle: ["error", {"functions": "always"}]*/
function foo(a, b) {
}
foo(a, b);
new foo(a, b);
Examples of correct code for this rule with the {"functions": "always"}
option:
/*eslint comma-dangle: ["error", {"functions": "always"}]*/
function foo(a, b,) {
}
foo(a, b,);
new foo(a, b,);
When Not To Use It
You can turn this rule off if you are not concerned with dangling commas. Source: http://eslint.org/docs/rules/
Unexpected console statement. Open
console.log(
- Read upRead up
- Exclude checks
disallow the use of console
(no-console)
In JavaScript that is designed to be executed in the browser, it's considered a best practice to avoid using methods on console
. Such messages are considered to be for debugging purposes and therefore not suitable to ship to the client. In general, calls using console
should be stripped before being pushed to production.
console.log("Made it here.");
console.error("That shouldn't have happened.");
Rule Details
This rule disallows calls to methods of the console
object.
Examples of incorrect code for this rule:
/*eslint no-console: "error"*/
console.log("Log a debug level message.");
console.warn("Log a warn level message.");
console.error("Log an error level message.");
Examples of correct code for this rule:
/*eslint no-console: "error"*/
// custom console
Console.log("Hello world!");
Options
This rule has an object option for exceptions:
-
"allow"
has an array of strings which are allowed methods of theconsole
object
Examples of additional correct code for this rule with a sample { "allow": ["warn", "error"] }
option:
/*eslint no-console: ["error", { allow: ["warn", "error"] }] */
console.warn("Log a warn level message.");
console.error("Log an error level message.");
When Not To Use It
If you're using Node.js, however, console
is used to output information to the user and so is not strictly used for debugging purposes. If you are developing for Node.js then you most likely do not want this rule enabled.
Related Rules
- [no-alert](no-alert.md)
- [no-debugger](no-debugger.md) Source: http://eslint.org/docs/rules/
Missing space before function parentheses. Open
onProxyReq: function(proxyReq, req, res) {
- Read upRead up
- Exclude checks
Require or disallow a space before function parenthesis (space-before-function-paren)
When formatting a function, whitespace is allowed between the function name or function
keyword and the opening paren. Named functions also require a space between the function
keyword and the function name, but anonymous functions require no whitespace. For example:
function withoutSpace(x) {
// ...
}
function withSpace (x) {
// ...
}
var anonymousWithoutSpace = function() {};
var anonymousWithSpace = function () {};
Style guides may require a space after the function
keyword for anonymous functions, while others specify no whitespace. Similarly, the space after a function name may or may not be required.
Rule Details
This rule aims to enforce consistent spacing before function parentheses and as such, will warn whenever whitespace doesn't match the preferences specified.
Options
This rule has a string option or an object option:
{
"space-before-function-paren": ["error", "always"],
// or
"space-before-function-paren": ["error", {
"anonymous": "always",
"named": "always",
"asyncArrow": "ignore"
}],
}
-
always
(default) requires a space followed by the(
of arguments. -
never
disallows any space followed by the(
of arguments.
The string option does not check async arrow function expressions for backward compatibility.
You can also use a separate option for each type of function.
Each of the following options can be set to "always"
, "never"
, or "ignore"
.
Default is "always"
basically.
-
anonymous
is for anonymous function expressions (e.g.function () {}
). -
named
is for named function expressions (e.g.function foo () {}
). -
asyncArrow
is for async arrow function expressions (e.g.async () => {}
).asyncArrow
is set to"ignore"
by default for backwards compatibility.
"always"
Examples of incorrect code for this rule with the default "always"
option:
/*eslint space-before-function-paren: "error"*/
/*eslint-env es6*/
function foo() {
// ...
}
var bar = function() {
// ...
};
var bar = function foo() {
// ...
};
class Foo {
constructor() {
// ...
}
}
var foo = {
bar() {
// ...
}
};
Examples of correct code for this rule with the default "always"
option:
/*eslint space-before-function-paren: "error"*/
/*eslint-env es6*/
function foo () {
// ...
}
var bar = function () {
// ...
};
var bar = function foo () {
// ...
};
class Foo {
constructor () {
// ...
}
}
var foo = {
bar () {
// ...
}
};
// async arrow function expressions are ignored by default.
var foo = async () => 1
var foo = async() => 1
"never"
Examples of incorrect code for this rule with the "never"
option:
/*eslint space-before-function-paren: ["error", "never"]*/
/*eslint-env es6*/
function foo () {
// ...
}
var bar = function () {
// ...
};
var bar = function foo () {
// ...
};
class Foo {
constructor () {
// ...
}
}
var foo = {
bar () {
// ...
}
};
Examples of correct code for this rule with the "never"
option:
/*eslint space-before-function-paren: ["error", "never"]*/
/*eslint-env es6*/
function foo() {
// ...
}
var bar = function() {
// ...
};
var bar = function foo() {
// ...
};
class Foo {
constructor() {
// ...
}
}
var foo = {
bar() {
// ...
}
};
// async arrow function expressions are ignored by default.
var foo = async () => 1
var foo = async() => 1
{"anonymous": "always", "named": "never", "asyncArrow": "always"}
Examples of incorrect code for this rule with the {"anonymous": "always", "named": "never", "asyncArrow": "always"}
option:
/*eslint space-before-function-paren: ["error", {"anonymous": "always", "named": "never", "asyncArrow": "always"}]*/
/*eslint-env es6*/
function foo () {
// ...
}
var bar = function() {
// ...
};
class Foo {
constructor () {
// ...
}
}
var foo = {
bar () {
// ...
}
};
var foo = async(a) => await a
Examples of correct code for this rule with the {"anonymous": "always", "named": "never", "asyncArrow": "always"}
option:
/*eslint space-before-function-paren: ["error", {"anonymous": "always", "named": "never", "asyncArrow": "always"}]*/
/*eslint-env es6*/
function foo() {
// ...
}
var bar = function () {
// ...
};
class Foo {
constructor() {
// ...
}
}
var foo = {
bar() {
// ...
}
};
var foo = async (a) => await a
{"anonymous": "never", "named": "always"}
Examples of incorrect code for this rule with the {"anonymous": "never", "named": "always"}
option:
/*eslint space-before-function-paren: ["error", { "anonymous": "never", "named": "always" }]*/
/*eslint-env es6*/
function foo() {
// ...
}
var bar = function () {
// ...
};
class Foo {
constructor() {
// ...
}
}
var foo = {
bar() {
// ...
}
};
Examples of correct code for this rule with the {"anonymous": "never", "named": "always"}
option:
/*eslint space-before-function-paren: ["error", { "anonymous": "never", "named": "always" }]*/
/*eslint-env es6*/
function foo () {
// ...
}
var bar = function() {
// ...
};
class Foo {
constructor () {
// ...
}
}
var foo = {
bar () {
// ...
}
};
{"anonymous": "ignore", "named": "always"}
Examples of incorrect code for this rule with the {"anonymous": "ignore", "named": "always"}
option:
/*eslint space-before-function-paren: ["error", { "anonymous": "ignore", "named": "always" }]*/
/*eslint-env es6*/
function foo() {
// ...
}
class Foo {
constructor() {
// ...
}
}
var foo = {
bar() {
// ...
}
};
Examples of correct code for this rule with the {"anonymous": "ignore", "named": "always"}
option:
/*eslint space-before-function-paren: ["error", { "anonymous": "ignore", "named": "always" }]*/
/*eslint-env es6*/
var bar = function() {
// ...
};
var bar = function () {
// ...
};
function foo () {
// ...
}
class Foo {
constructor () {
// ...
}
}
var foo = {
bar () {
// ...
}
};
When Not To Use It
You can turn this rule off if you are not concerned with the consistency of spacing before function parenthesis.
Related Rules
- [space-after-keywords](space-after-keywords.md)
- [space-return-throw-case](space-return-throw-case.md) Source: http://eslint.org/docs/rules/
Unexpected console statement. Open
console.log(chalk.red('Instead, the type of "proxy" was "' + typeof proxy + '".'));
- Read upRead up
- Exclude checks
disallow the use of console
(no-console)
In JavaScript that is designed to be executed in the browser, it's considered a best practice to avoid using methods on console
. Such messages are considered to be for debugging purposes and therefore not suitable to ship to the client. In general, calls using console
should be stripped before being pushed to production.
console.log("Made it here.");
console.error("That shouldn't have happened.");
Rule Details
This rule disallows calls to methods of the console
object.
Examples of incorrect code for this rule:
/*eslint no-console: "error"*/
console.log("Log a debug level message.");
console.warn("Log a warn level message.");
console.error("Log an error level message.");
Examples of correct code for this rule:
/*eslint no-console: "error"*/
// custom console
Console.log("Hello world!");
Options
This rule has an object option for exceptions:
-
"allow"
has an array of strings which are allowed methods of theconsole
object
Examples of additional correct code for this rule with a sample { "allow": ["warn", "error"] }
option:
/*eslint no-console: ["error", { allow: ["warn", "error"] }] */
console.warn("Log a warn level message.");
console.error("Log an error level message.");
When Not To Use It
If you're using Node.js, however, console
is used to output information to the user and so is not strictly used for debugging purposes. If you are developing for Node.js then you most likely do not want this rule enabled.
Related Rules
- [no-alert](no-alert.md)
- [no-debugger](no-debugger.md) Source: http://eslint.org/docs/rules/
Unexpected unnamed method 'onProxyReq'. Open
onProxyReq: function(proxyReq, req, res) {
- Read upRead up
- Exclude checks
Require or disallow named function
expressions (func-names)
A pattern that's becoming more common is to give function expressions names to aid in debugging. For example:
Foo.prototype.bar = function bar() {};
Adding the second bar
in the above example is optional. If you leave off the function name then when the function throws an exception you are likely to get something similar to anonymous function
in the stack trace. If you provide the optional name for a function expression then you will get the name of the function expression in the stack trace.
Rule Details
This rule can enforce or disallow the use of named function expressions.
Options
This rule has a string option:
-
"always"
(default) requires function expressions to have a name -
"as-needed"
requires function expressions to have a name, if the name cannot be assigned automatically in an ES6 environment -
"never"
disallows named function expressions, except in recursive functions, where a name is needed
always
Examples of incorrect code for this rule with the default "always"
option:
/*eslint func-names: ["error", "always"]*/
Foo.prototype.bar = function() {};
(function() {
// ...
}())
Examples of correct code for this rule with the default "always"
option:
/*eslint func-names: ["error", "always"]*/
Foo.prototype.bar = function bar() {};
(function bar() {
// ...
}())
as-needed
ECMAScript 6 introduced a name
property on all functions. The value of name
is determined by evaluating the code around the function to see if a name can be inferred. For example, a function assigned to a variable will automatically have a name
property equal to the name of the variable. The value of name
is then used in stack traces for easier debugging.
Examples of incorrect code for this rule with the default "as-needed"
option:
/*eslint func-names: ["error", "as-needed"]*/
Foo.prototype.bar = function() {};
(function() {
// ...
}())
Examples of correct code for this rule with the default "as-needed"
option:
/*eslint func-names: ["error", "as-needed"]*/
var bar = function() {};
(function bar() {
// ...
}())
never
Examples of incorrect code for this rule with the "never"
option:
/*eslint func-names: ["error", "never"]*/
Foo.prototype.bar = function bar() {};
(function bar() {
// ...
}())
Examples of correct code for this rule with the "never"
option:
/*eslint func-names: ["error", "never"]*/
Foo.prototype.bar = function() {};
(function() {
// ...
}())
Further Reading
Compatibility
- JSCS: requireAnonymousFunctions
- JSCS: disallowAnonymousFunctions Source: http://eslint.org/docs/rules/