Forbidden 'var' keyword, use 'let' or 'const' instead Open
var myIndex = store.index('id');
- Read upRead up
- Exclude checks
Rule: no-var-keyword
Disallows usage of the var
keyword.
Use let
or const
instead.
Rationale
Declaring variables using var
has several edge case behaviors that make var
unsuitable for modern code.
Variables declared by var
have their parent function block as their scope, ignoring other control flow statements.
var
s have declaration "hoisting" (similar to function
s) and can appear to be used before declaration.
Variables declared by const
and let
instead have as their scope the block in which they are defined,
and are not allowed to used before declaration or be re-declared with another const
or let
.
Notes
- Has Fix
Config
Not configurable.
Examples
"no-var-keyword": true
For more information see this page.
Identifier 'request' is never reassigned; use 'const' instead of 'let'. Open
let request = store.getKey(id);
- Read upRead up
- Exclude checks
Rule: prefer-const
Requires that variable declarations use const
instead of let
and var
if possible.
If a variable is only assigned to once when it is declared, it should be declared using 'const'
Notes
- Has Fix
Config
An optional object containing the property "destructuring" with two possible values:
- "any" (default) - If any variable in destructuring can be const, this rule warns for those variables.
- "all" - Only warns if all variables in destructuring can be const.
Examples
"prefer-const": true
"prefer-const": true,[object Object]
Schema
{
"type": "object",
"properties": {
"destructuring": {
"type": "string",
"enum": [
"all",
"any"
]
}
}
}
For more information see this page.
comment must start with a space Open
//this.db.createObjectStore(this._dbName)
- Read upRead up
- Exclude checks
Rule: comment-format
Enforces formatting rules for single-line comments.
Rationale
Helps maintain a consistent, readable style in your codebase.
Notes
- Has Fix
Config
Four arguments may be optionally provided:
-
"check-space"
requires that all single-line comments must begin with a space, as in// comment
- note that for comments starting with multiple slashes, e.g.
///
, leading slashes are ignored - TypeScript reference comments are ignored completely
- note that for comments starting with multiple slashes, e.g.
-
"check-lowercase"
requires that the first non-whitespace character of a comment must be lowercase, if applicable. -
"check-uppercase"
requires that the first non-whitespace character of a comment must be uppercase, if applicable. -
"allow-trailing-lowercase"
allows that only the first comment of a series of comments needs to be uppercase.- requires
"check-uppercase"
- comments must start at the same position
- requires
Exceptions to "check-lowercase"
or "check-uppercase"
can be managed with object that may be passed as last
argument.
One of two options can be provided in this object:
-
"ignore-words"
- array of strings - words that will be ignored at the beginning of the comment. -
"ignore-pattern"
- string - RegExp pattern that will be ignored at the beginning of the comment.
Examples
"comment-format": true,check-space,check-uppercase,allow-trailing-lowercase
"comment-format": true,check-lowercase,[object Object]
"comment-format": true,check-lowercase,[object Object]
Schema
{
"type": "array",
"items": {
"anyOf": [
{
"type": "string",
"enum": [
"check-space",
"check-lowercase",
"check-uppercase",
"allow-trailing-lowercase"
]
},
{
"type": "object",
"properties": {
"ignore-words": {
"type": "array",
"items": {
"type": "string"
}
},
"ignore-pattern": {
"type": "string"
}
},
"minProperties": 1,
"maxProperties": 1
}
]
},
"minLength": 1,
"maxLength": 5
}
For more information see this page.
comment must start with a space Open
//TODO: parallel?
- Read upRead up
- Exclude checks
Rule: comment-format
Enforces formatting rules for single-line comments.
Rationale
Helps maintain a consistent, readable style in your codebase.
Notes
- Has Fix
Config
Four arguments may be optionally provided:
-
"check-space"
requires that all single-line comments must begin with a space, as in// comment
- note that for comments starting with multiple slashes, e.g.
///
, leading slashes are ignored - TypeScript reference comments are ignored completely
- note that for comments starting with multiple slashes, e.g.
-
"check-lowercase"
requires that the first non-whitespace character of a comment must be lowercase, if applicable. -
"check-uppercase"
requires that the first non-whitespace character of a comment must be uppercase, if applicable. -
"allow-trailing-lowercase"
allows that only the first comment of a series of comments needs to be uppercase.- requires
"check-uppercase"
- comments must start at the same position
- requires
Exceptions to "check-lowercase"
or "check-uppercase"
can be managed with object that may be passed as last
argument.
One of two options can be provided in this object:
-
"ignore-words"
- array of strings - words that will be ignored at the beginning of the comment. -
"ignore-pattern"
- string - RegExp pattern that will be ignored at the beginning of the comment.
Examples
"comment-format": true,check-space,check-uppercase,allow-trailing-lowercase
"comment-format": true,check-lowercase,[object Object]
"comment-format": true,check-lowercase,[object Object]
Schema
{
"type": "array",
"items": {
"anyOf": [
{
"type": "string",
"enum": [
"check-space",
"check-lowercase",
"check-uppercase",
"allow-trailing-lowercase"
]
},
{
"type": "object",
"properties": {
"ignore-words": {
"type": "array",
"items": {
"type": "string"
}
},
"ignore-pattern": {
"type": "string"
}
},
"minProperties": 1,
"maxProperties": 1
}
]
},
"minLength": 1,
"maxLength": 5
}
For more information see this page.
Identifier 'objectStore' is never reassigned; use 'const' instead of 'let'. Open
let objectStore = db.createObjectStore(this._objectStoreName, { keyPath: "id" });
- Read upRead up
- Exclude checks
Rule: prefer-const
Requires that variable declarations use const
instead of let
and var
if possible.
If a variable is only assigned to once when it is declared, it should be declared using 'const'
Notes
- Has Fix
Config
An optional object containing the property "destructuring" with two possible values:
- "any" (default) - If any variable in destructuring can be const, this rule warns for those variables.
- "all" - Only warns if all variables in destructuring can be const.
Examples
"prefer-const": true
"prefer-const": true,[object Object]
Schema
{
"type": "object",
"properties": {
"destructuring": {
"type": "string",
"enum": [
"all",
"any"
]
}
}
}
For more information see this page.
Unnecessary semicolon Open
if (!Array.isArray(records)) { records = [records] };
- Read upRead up
- Exclude checks
Rule: semicolon
Enforces consistent semicolon usage at the end of every statement.
Notes
- Has Fix
Config
One of the following arguments must be provided:
-
"always"
enforces semicolons at the end of every statement. -
"never"
disallows semicolons at the end of every statement except for when they are necessary.
The following arguments may be optionally provided:
-
"ignore-interfaces"
skips checking semicolons at the end of interface members. -
"ignore-bound-class-methods"
skips checking semicolons at the end of bound class methods. -
"strict-bound-class-methods"
disables any special handling of bound class methods and treats them as any other assignment. This option overrides"ignore-bound-class-methods"
.
Examples
"semicolon": true,always
"semicolon": true,never
"semicolon": true,always,ignore-interfaces
"semicolon": true,always,ignore-bound-class-methods
Schema
{
"type": "array",
"items": [
{
"type": "string",
"enum": [
"always",
"never"
]
},
{
"type": "string",
"enum": [
"ignore-interfaces"
]
}
],
"additionalItems": false
}
For more information see this page.
comment must start with a space Open
//this._push.push(record);
- Read upRead up
- Exclude checks
Rule: comment-format
Enforces formatting rules for single-line comments.
Rationale
Helps maintain a consistent, readable style in your codebase.
Notes
- Has Fix
Config
Four arguments may be optionally provided:
-
"check-space"
requires that all single-line comments must begin with a space, as in// comment
- note that for comments starting with multiple slashes, e.g.
///
, leading slashes are ignored - TypeScript reference comments are ignored completely
- note that for comments starting with multiple slashes, e.g.
-
"check-lowercase"
requires that the first non-whitespace character of a comment must be lowercase, if applicable. -
"check-uppercase"
requires that the first non-whitespace character of a comment must be uppercase, if applicable. -
"allow-trailing-lowercase"
allows that only the first comment of a series of comments needs to be uppercase.- requires
"check-uppercase"
- comments must start at the same position
- requires
Exceptions to "check-lowercase"
or "check-uppercase"
can be managed with object that may be passed as last
argument.
One of two options can be provided in this object:
-
"ignore-words"
- array of strings - words that will be ignored at the beginning of the comment. -
"ignore-pattern"
- string - RegExp pattern that will be ignored at the beginning of the comment.
Examples
"comment-format": true,check-space,check-uppercase,allow-trailing-lowercase
"comment-format": true,check-lowercase,[object Object]
"comment-format": true,check-lowercase,[object Object]
Schema
{
"type": "array",
"items": {
"anyOf": [
{
"type": "string",
"enum": [
"check-space",
"check-lowercase",
"check-uppercase",
"allow-trailing-lowercase"
]
},
{
"type": "object",
"properties": {
"ignore-words": {
"type": "array",
"items": {
"type": "string"
}
},
"ignore-pattern": {
"type": "string"
}
},
"minProperties": 1,
"maxProperties": 1
}
]
},
"minLength": 1,
"maxLength": 5
}
For more information see this page.
Identifier 'request' is never reassigned; use 'const' instead of 'let'. Open
let request = indexedDB.open(this._dbName, 1);
- Read upRead up
- Exclude checks
Rule: prefer-const
Requires that variable declarations use const
instead of let
and var
if possible.
If a variable is only assigned to once when it is declared, it should be declared using 'const'
Notes
- Has Fix
Config
An optional object containing the property "destructuring" with two possible values:
- "any" (default) - If any variable in destructuring can be const, this rule warns for those variables.
- "all" - Only warns if all variables in destructuring can be const.
Examples
"prefer-const": true
"prefer-const": true,[object Object]
Schema
{
"type": "object",
"properties": {
"destructuring": {
"type": "string",
"enum": [
"all",
"any"
]
}
}
}
For more information see this page.
Shadowed name: 'resolve' Open
return new Promise<IRecord[]>((resolve, reject) => {
- Read upRead up
- Exclude checks
Rule: no-shadowed-variable
Disallows shadowing variable declarations.
Rationale
When a variable in a local scope and a variable in the containing scope have the same name, shadowing occurs. Shadowing makes it impossible to access the variable in the containing scope and obscures to what value an identifier actually refers. Compare the following snippets:
const a = 'no shadow';
function print() {
console.log(a);
}
print(); // logs 'no shadow'.
const a = 'no shadow';
function print() {
const a = 'shadow'; // TSLint will complain here.
console.log(a);
}
print(); // logs 'shadow'.
ESLint has an equivalent rule. For more background information, refer to this MDN closure doc.
Config
You can optionally pass an object to disable checking for certain kinds of declarations.
Possible keys are "class"
, "enum"
, "function"
, "import"
, "interface"
, "namespace"
, "typeAlias"
and "typeParameter"
. You can also pass "underscore
" to ignore variable names that begin with _
.
Just set the value to false
for the check you want to disable.
All checks default to true
, i.e. are enabled by default.
Note that you cannot disable variables and parameters.
The option "temporalDeadZone"
defaults to true
which shows errors when shadowing block scoped declarations in their
temporal dead zone. When set to false
parameters, classes, enums and variables declared
with let
or const
are not considered shadowed if the shadowing occurs within their
temporal dead zone.
The following example shows how the "temporalDeadZone"
option changes the linting result:
function fn(value) {
if (value) {
const tmp = value; // no error on this line if "temporalDeadZone" is false
return tmp;
}
let tmp = undefined;
if (!value) {
const tmp = value; // this line always contains an error
return tmp;
}
}
Examples
"no-shadowed-variable": true
"no-shadowed-variable": true,[object Object]
Schema
{
"type": "object",
"properties": {
"class": {
"type": "boolean"
},
"enum": {
"type": "boolean"
},
"function": {
"type": "boolean"
},
"import": {
"type": "boolean"
},
"interface": {
"type": "boolean"
},
"namespace": {
"type": "boolean"
},
"typeAlias": {
"type": "boolean"
},
"typeParameter": {
"type": "boolean"
},
"temporalDeadZone": {
"type": "boolean"
},
"underscore": {
"type": "boolean"
}
}
}
For more information see this page.
Identifier 'store' is never reassigned; use 'const' instead of 'let'. Open
let store = this.db.transaction([this._objectStoreName])
- Read upRead up
- Exclude checks
Rule: prefer-const
Requires that variable declarations use const
instead of let
and var
if possible.
If a variable is only assigned to once when it is declared, it should be declared using 'const'
Notes
- Has Fix
Config
An optional object containing the property "destructuring" with two possible values:
- "any" (default) - If any variable in destructuring can be const, this rule warns for those variables.
- "all" - Only warns if all variables in destructuring can be const.
Examples
"prefer-const": true
"prefer-const": true,[object Object]
Schema
{
"type": "object",
"properties": {
"destructuring": {
"type": "string",
"enum": [
"all",
"any"
]
}
}
}
For more information see this page.
Shadowed name: 'resolve' Open
return new Promise<IRecord>((resolve, reject) => {
- Read upRead up
- Exclude checks
Rule: no-shadowed-variable
Disallows shadowing variable declarations.
Rationale
When a variable in a local scope and a variable in the containing scope have the same name, shadowing occurs. Shadowing makes it impossible to access the variable in the containing scope and obscures to what value an identifier actually refers. Compare the following snippets:
const a = 'no shadow';
function print() {
console.log(a);
}
print(); // logs 'no shadow'.
const a = 'no shadow';
function print() {
const a = 'shadow'; // TSLint will complain here.
console.log(a);
}
print(); // logs 'shadow'.
ESLint has an equivalent rule. For more background information, refer to this MDN closure doc.
Config
You can optionally pass an object to disable checking for certain kinds of declarations.
Possible keys are "class"
, "enum"
, "function"
, "import"
, "interface"
, "namespace"
, "typeAlias"
and "typeParameter"
. You can also pass "underscore
" to ignore variable names that begin with _
.
Just set the value to false
for the check you want to disable.
All checks default to true
, i.e. are enabled by default.
Note that you cannot disable variables and parameters.
The option "temporalDeadZone"
defaults to true
which shows errors when shadowing block scoped declarations in their
temporal dead zone. When set to false
parameters, classes, enums and variables declared
with let
or const
are not considered shadowed if the shadowing occurs within their
temporal dead zone.
The following example shows how the "temporalDeadZone"
option changes the linting result:
function fn(value) {
if (value) {
const tmp = value; // no error on this line if "temporalDeadZone" is false
return tmp;
}
let tmp = undefined;
if (!value) {
const tmp = value; // this line always contains an error
return tmp;
}
}
Examples
"no-shadowed-variable": true
"no-shadowed-variable": true,[object Object]
Schema
{
"type": "object",
"properties": {
"class": {
"type": "boolean"
},
"enum": {
"type": "boolean"
},
"function": {
"type": "boolean"
},
"import": {
"type": "boolean"
},
"interface": {
"type": "boolean"
},
"namespace": {
"type": "boolean"
},
"typeAlias": {
"type": "boolean"
},
"typeParameter": {
"type": "boolean"
},
"temporalDeadZone": {
"type": "boolean"
},
"underscore": {
"type": "boolean"
}
}
}
For more information see this page.
Forbidden 'var' keyword, use 'let' or 'const' instead Open
var request = store
- Read upRead up
- Exclude checks
Rule: no-var-keyword
Disallows usage of the var
keyword.
Use let
or const
instead.
Rationale
Declaring variables using var
has several edge case behaviors that make var
unsuitable for modern code.
Variables declared by var
have their parent function block as their scope, ignoring other control flow statements.
var
s have declaration "hoisting" (similar to function
s) and can appear to be used before declaration.
Variables declared by const
and let
instead have as their scope the block in which they are defined,
and are not allowed to used before declaration or be re-declared with another const
or let
.
Notes
- Has Fix
Config
Not configurable.
Examples
"no-var-keyword": true
For more information see this page.
Identifier 'store' is never reassigned; use 'const' instead of 'let'. Open
let store = this.db.transaction([this._objectStoreName])
- Read upRead up
- Exclude checks
Rule: prefer-const
Requires that variable declarations use const
instead of let
and var
if possible.
If a variable is only assigned to once when it is declared, it should be declared using 'const'
Notes
- Has Fix
Config
An optional object containing the property "destructuring" with two possible values:
- "any" (default) - If any variable in destructuring can be const, this rule warns for those variables.
- "all" - Only warns if all variables in destructuring can be const.
Examples
"prefer-const": true
"prefer-const": true,[object Object]
Schema
{
"type": "object",
"properties": {
"destructuring": {
"type": "string",
"enum": [
"all",
"any"
]
}
}
}
For more information see this page.
Missing semicolon Open
let storedRecord = await this.GetRecordById(record.id)
- Read upRead up
- Exclude checks
Rule: semicolon
Enforces consistent semicolon usage at the end of every statement.
Notes
- Has Fix
Config
One of the following arguments must be provided:
-
"always"
enforces semicolons at the end of every statement. -
"never"
disallows semicolons at the end of every statement except for when they are necessary.
The following arguments may be optionally provided:
-
"ignore-interfaces"
skips checking semicolons at the end of interface members. -
"ignore-bound-class-methods"
skips checking semicolons at the end of bound class methods. -
"strict-bound-class-methods"
disables any special handling of bound class methods and treats them as any other assignment. This option overrides"ignore-bound-class-methods"
.
Examples
"semicolon": true,always
"semicolon": true,never
"semicolon": true,always,ignore-interfaces
"semicolon": true,always,ignore-bound-class-methods
Schema
{
"type": "array",
"items": [
{
"type": "string",
"enum": [
"always",
"never"
]
},
{
"type": "string",
"enum": [
"ignore-interfaces"
]
}
],
"additionalItems": false
}
For more information see this page.
comment must start with a space Open
//import localforage from "localforage";
- Read upRead up
- Exclude checks
Rule: comment-format
Enforces formatting rules for single-line comments.
Rationale
Helps maintain a consistent, readable style in your codebase.
Notes
- Has Fix
Config
Four arguments may be optionally provided:
-
"check-space"
requires that all single-line comments must begin with a space, as in// comment
- note that for comments starting with multiple slashes, e.g.
///
, leading slashes are ignored - TypeScript reference comments are ignored completely
- note that for comments starting with multiple slashes, e.g.
-
"check-lowercase"
requires that the first non-whitespace character of a comment must be lowercase, if applicable. -
"check-uppercase"
requires that the first non-whitespace character of a comment must be uppercase, if applicable. -
"allow-trailing-lowercase"
allows that only the first comment of a series of comments needs to be uppercase.- requires
"check-uppercase"
- comments must start at the same position
- requires
Exceptions to "check-lowercase"
or "check-uppercase"
can be managed with object that may be passed as last
argument.
One of two options can be provided in this object:
-
"ignore-words"
- array of strings - words that will be ignored at the beginning of the comment. -
"ignore-pattern"
- string - RegExp pattern that will be ignored at the beginning of the comment.
Examples
"comment-format": true,check-space,check-uppercase,allow-trailing-lowercase
"comment-format": true,check-lowercase,[object Object]
"comment-format": true,check-lowercase,[object Object]
Schema
{
"type": "array",
"items": {
"anyOf": [
{
"type": "string",
"enum": [
"check-space",
"check-lowercase",
"check-uppercase",
"allow-trailing-lowercase"
]
},
{
"type": "object",
"properties": {
"ignore-words": {
"type": "array",
"items": {
"type": "string"
}
},
"ignore-pattern": {
"type": "string"
}
},
"minProperties": 1,
"maxProperties": 1
}
]
},
"minLength": 1,
"maxLength": 5
}
For more information see this page.
non-arrow functions are forbidden Open
getAllKeysRequest.onsuccess = function () {
- Read upRead up
- Exclude checks
Rule: only-arrow-functions
Disallows traditional (non-arrow) function expressions.
Note that non-arrow functions are allowed if 'this' appears somewhere in its body (as such functions cannot be converted to arrow functions).
Rationale
Traditional functions don't bind lexical scope, which can lead to unexpected behavior when accessing 'this'.
Config
Two arguments may be optionally provided:
-
"allow-declarations"
allows standalone function declarations. -
"allow-named-functions"
allows the expressionfunction foo() {}
but notfunction() {}
.
Examples
"only-arrow-functions": true
"only-arrow-functions": true,allow-declarations,allow-named-functions
Schema
{
"type": "array",
"items": {
"type": "string",
"enum": [
"allow-declarations",
"allow-named-functions"
]
},
"minLength": 0,
"maxLength": 1
}
For more information see this page.
" should be ' Open
import StoreBase from "./StoreBase";
- Read upRead up
- Exclude checks
Rule: quotemark
Enforces quote character for string literals.
Notes
- Has Fix
Config
Five arguments may be optionally provided:
-
"single"
enforces single quotes. -
"double"
enforces double quotes. -
"backtick"
enforces backticks. -
"jsx-single"
enforces single quotes for JSX attributes. -
"jsx-double"
enforces double quotes for JSX attributes. -
"avoid-template"
forbids single-line untagged template strings that do not contain string interpolations. Note that backticks may still be used if"avoid-escape"
is enabled and both single and double quotes are present in the string (the latter option takes precedence). -
"avoid-escape"
allows you to use the "other" quotemark in cases where escaping would normally be required. For example,[true, "double", "avoid-escape"]
would not report a failure on the string literal'Hello "World"'
.
Examples
"quotemark": true,single,avoid-escape,avoid-template
"quotemark": true,single,jsx-double
Schema
{
"type": "array",
"items": {
"type": "string",
"enum": [
"single",
"double",
"backtick",
"jsx-single",
"jsx-double",
"avoid-escape",
"avoid-template"
]
},
"minLength": 0,
"maxLength": 5
}
For more information see this page.
Identifier 'storedRecord' is never reassigned; use 'const' instead of 'let'. Open
let storedRecord = await this.GetRecordById(record.id)
- Read upRead up
- Exclude checks
Rule: prefer-const
Requires that variable declarations use const
instead of let
and var
if possible.
If a variable is only assigned to once when it is declared, it should be declared using 'const'
Notes
- Has Fix
Config
An optional object containing the property "destructuring" with two possible values:
- "any" (default) - If any variable in destructuring can be const, this rule warns for those variables.
- "all" - Only warns if all variables in destructuring can be const.
Examples
"prefer-const": true
"prefer-const": true,[object Object]
Schema
{
"type": "object",
"properties": {
"destructuring": {
"type": "string",
"enum": [
"all",
"any"
]
}
}
}
For more information see this page.
Identifier 'store' is never reassigned; use 'const' instead of 'let'. Open
let store = this.db.transaction([this._objectStoreName], 'readwrite')
- Read upRead up
- Exclude checks
Rule: prefer-const
Requires that variable declarations use const
instead of let
and var
if possible.
If a variable is only assigned to once when it is declared, it should be declared using 'const'
Notes
- Has Fix
Config
An optional object containing the property "destructuring" with two possible values:
- "any" (default) - If any variable in destructuring can be const, this rule warns for those variables.
- "all" - Only warns if all variables in destructuring can be const.
Examples
"prefer-const": true
"prefer-const": true,[object Object]
Schema
{
"type": "object",
"properties": {
"destructuring": {
"type": "string",
"enum": [
"all",
"any"
]
}
}
}
For more information see this page.
missing whitespace Open
request.onsuccess = (event) => { resolve((typeof request.result ==='string' ? JSON.parse(request.result as string) : request.result) as IRecord) };
- Read upRead up
- Exclude checks
Rule: whitespace
Enforces whitespace style conventions.
Rationale
Helps maintain a readable, consistent style in your codebase.
Notes
- Has Fix
Config
Several arguments may be optionally provided:
-
"check-branch"
checks branching statements (if
/else
/for
/while
) are followed by whitespace. -
"check-decl"
checks that variable declarations have whitespace around the equals token. -
"check-operator"
checks for whitespace around operator tokens. -
"check-module"
checks for whitespace in import & export statements. -
"check-separator"
checks for whitespace after separator tokens (,
/;
). -
"check-rest-spread"
checks that there is no whitespace after rest/spread operator (...
). -
"check-type"
checks for whitespace before a variable type specification. -
"check-typecast"
checks for whitespace between a typecast and its target. -
"check-type-operator"
checks for whitespace between type operators|
and&
. -
"check-preblock"
checks for whitespace before the opening brace of a block. -
"check-postbrace"
checks for whitespace after an opening brace.
Examples
"whitespace": true,check-branch,check-operator,check-typecast
Schema
{
"type": "array",
"items": {
"type": "string",
"enum": [
"check-branch",
"check-decl",
"check-operator",
"check-module",
"check-separator",
"check-rest-spread",
"check-type",
"check-typecast",
"check-type-operator",
"check-preblock",
"check-postbrace"
]
},
"minLength": 0,
"maxLength": 11
}
For more information see this page.
missing whitespace Open
const isArray = Array.isArray(records);//DAMN TS COMPILER.
- Read upRead up
- Exclude checks
Rule: whitespace
Enforces whitespace style conventions.
Rationale
Helps maintain a readable, consistent style in your codebase.
Notes
- Has Fix
Config
Several arguments may be optionally provided:
-
"check-branch"
checks branching statements (if
/else
/for
/while
) are followed by whitespace. -
"check-decl"
checks that variable declarations have whitespace around the equals token. -
"check-operator"
checks for whitespace around operator tokens. -
"check-module"
checks for whitespace in import & export statements. -
"check-separator"
checks for whitespace after separator tokens (,
/;
). -
"check-rest-spread"
checks that there is no whitespace after rest/spread operator (...
). -
"check-type"
checks for whitespace before a variable type specification. -
"check-typecast"
checks for whitespace between a typecast and its target. -
"check-type-operator"
checks for whitespace between type operators|
and&
. -
"check-preblock"
checks for whitespace before the opening brace of a block. -
"check-postbrace"
checks for whitespace after an opening brace.
Examples
"whitespace": true,check-branch,check-operator,check-typecast
Schema
{
"type": "array",
"items": {
"type": "string",
"enum": [
"check-branch",
"check-decl",
"check-operator",
"check-module",
"check-separator",
"check-rest-spread",
"check-type",
"check-typecast",
"check-type-operator",
"check-preblock",
"check-postbrace"
]
},
"minLength": 0,
"maxLength": 11
}
For more information see this page.
file should end with a newline Open
}
- Read upRead up
- Exclude checks
Rule: eofline
Ensures the file ends with a newline.
Fix for single-line files is not supported.
Rationale
It is a standard convention to end files with a newline.
Notes
- Has Fix
Config
Not configurable.
Examples
"eofline": true
For more information see this page.
Identifier 'db' is never reassigned; use 'const' instead of 'let'. Open
let db: IDBDatabase = event.target.result;
- Read upRead up
- Exclude checks
Rule: prefer-const
Requires that variable declarations use const
instead of let
and var
if possible.
If a variable is only assigned to once when it is declared, it should be declared using 'const'
Notes
- Has Fix
Config
An optional object containing the property "destructuring" with two possible values:
- "any" (default) - If any variable in destructuring can be const, this rule warns for those variables.
- "all" - Only warns if all variables in destructuring can be const.
Examples
"prefer-const": true
"prefer-const": true,[object Object]
Schema
{
"type": "object",
"properties": {
"destructuring": {
"type": "string",
"enum": [
"all",
"any"
]
}
}
}
For more information see this page.
" should be ' Open
import IStore from "../IStore";
- Read upRead up
- Exclude checks
Rule: quotemark
Enforces quote character for string literals.
Notes
- Has Fix
Config
Five arguments may be optionally provided:
-
"single"
enforces single quotes. -
"double"
enforces double quotes. -
"backtick"
enforces backticks. -
"jsx-single"
enforces single quotes for JSX attributes. -
"jsx-double"
enforces double quotes for JSX attributes. -
"avoid-template"
forbids single-line untagged template strings that do not contain string interpolations. Note that backticks may still be used if"avoid-escape"
is enabled and both single and double quotes are present in the string (the latter option takes precedence). -
"avoid-escape"
allows you to use the "other" quotemark in cases where escaping would normally be required. For example,[true, "double", "avoid-escape"]
would not report a failure on the string literal'Hello "World"'
.
Examples
"quotemark": true,single,avoid-escape,avoid-template
"quotemark": true,single,jsx-double
Schema
{
"type": "array",
"items": {
"type": "string",
"enum": [
"single",
"double",
"backtick",
"jsx-single",
"jsx-double",
"avoid-escape",
"avoid-template"
]
},
"minLength": 0,
"maxLength": 5
}
For more information see this page.
" should be ' Open
import IRecord from "../IRecord";
- Read upRead up
- Exclude checks
Rule: quotemark
Enforces quote character for string literals.
Notes
- Has Fix
Config
Five arguments may be optionally provided:
-
"single"
enforces single quotes. -
"double"
enforces double quotes. -
"backtick"
enforces backticks. -
"jsx-single"
enforces single quotes for JSX attributes. -
"jsx-double"
enforces double quotes for JSX attributes. -
"avoid-template"
forbids single-line untagged template strings that do not contain string interpolations. Note that backticks may still be used if"avoid-escape"
is enabled and both single and double quotes are present in the string (the latter option takes precedence). -
"avoid-escape"
allows you to use the "other" quotemark in cases where escaping would normally be required. For example,[true, "double", "avoid-escape"]
would not report a failure on the string literal'Hello "World"'
.
Examples
"quotemark": true,single,avoid-escape,avoid-template
"quotemark": true,single,jsx-double
Schema
{
"type": "array",
"items": {
"type": "string",
"enum": [
"single",
"double",
"backtick",
"jsx-single",
"jsx-double",
"avoid-escape",
"avoid-template"
]
},
"minLength": 0,
"maxLength": 5
}
For more information see this page.
" should be ' Open
throw new Error("Method not implemented.");
- Read upRead up
- Exclude checks
Rule: quotemark
Enforces quote character for string literals.
Notes
- Has Fix
Config
Five arguments may be optionally provided:
-
"single"
enforces single quotes. -
"double"
enforces double quotes. -
"backtick"
enforces backticks. -
"jsx-single"
enforces single quotes for JSX attributes. -
"jsx-double"
enforces double quotes for JSX attributes. -
"avoid-template"
forbids single-line untagged template strings that do not contain string interpolations. Note that backticks may still be used if"avoid-escape"
is enabled and both single and double quotes are present in the string (the latter option takes precedence). -
"avoid-escape"
allows you to use the "other" quotemark in cases where escaping would normally be required. For example,[true, "double", "avoid-escape"]
would not report a failure on the string literal'Hello "World"'
.
Examples
"quotemark": true,single,avoid-escape,avoid-template
"quotemark": true,single,jsx-double
Schema
{
"type": "array",
"items": {
"type": "string",
"enum": [
"single",
"double",
"backtick",
"jsx-single",
"jsx-double",
"avoid-escape",
"avoid-template"
]
},
"minLength": 0,
"maxLength": 5
}
For more information see this page.
Missing semicolon Open
request.onsuccess = (event) => { resolve((typeof request.result ==='string' ? JSON.parse(request.result as string) : request.result) as IRecord) };
- Read upRead up
- Exclude checks
Rule: semicolon
Enforces consistent semicolon usage at the end of every statement.
Notes
- Has Fix
Config
One of the following arguments must be provided:
-
"always"
enforces semicolons at the end of every statement. -
"never"
disallows semicolons at the end of every statement except for when they are necessary.
The following arguments may be optionally provided:
-
"ignore-interfaces"
skips checking semicolons at the end of interface members. -
"ignore-bound-class-methods"
skips checking semicolons at the end of bound class methods. -
"strict-bound-class-methods"
disables any special handling of bound class methods and treats them as any other assignment. This option overrides"ignore-bound-class-methods"
.
Examples
"semicolon": true,always
"semicolon": true,never
"semicolon": true,always,ignore-interfaces
"semicolon": true,always,ignore-bound-class-methods
Schema
{
"type": "array",
"items": [
{
"type": "string",
"enum": [
"always",
"never"
]
},
{
"type": "string",
"enum": [
"ignore-interfaces"
]
}
],
"additionalItems": false
}
For more information see this page.
Shadowed name: 'resolve' Open
return new Promise<IRecord>(async (resolve, reject) => {
- Read upRead up
- Exclude checks
Rule: no-shadowed-variable
Disallows shadowing variable declarations.
Rationale
When a variable in a local scope and a variable in the containing scope have the same name, shadowing occurs. Shadowing makes it impossible to access the variable in the containing scope and obscures to what value an identifier actually refers. Compare the following snippets:
const a = 'no shadow';
function print() {
console.log(a);
}
print(); // logs 'no shadow'.
const a = 'no shadow';
function print() {
const a = 'shadow'; // TSLint will complain here.
console.log(a);
}
print(); // logs 'shadow'.
ESLint has an equivalent rule. For more background information, refer to this MDN closure doc.
Config
You can optionally pass an object to disable checking for certain kinds of declarations.
Possible keys are "class"
, "enum"
, "function"
, "import"
, "interface"
, "namespace"
, "typeAlias"
and "typeParameter"
. You can also pass "underscore
" to ignore variable names that begin with _
.
Just set the value to false
for the check you want to disable.
All checks default to true
, i.e. are enabled by default.
Note that you cannot disable variables and parameters.
The option "temporalDeadZone"
defaults to true
which shows errors when shadowing block scoped declarations in their
temporal dead zone. When set to false
parameters, classes, enums and variables declared
with let
or const
are not considered shadowed if the shadowing occurs within their
temporal dead zone.
The following example shows how the "temporalDeadZone"
option changes the linting result:
function fn(value) {
if (value) {
const tmp = value; // no error on this line if "temporalDeadZone" is false
return tmp;
}
let tmp = undefined;
if (!value) {
const tmp = value; // this line always contains an error
return tmp;
}
}
Examples
"no-shadowed-variable": true
"no-shadowed-variable": true,[object Object]
Schema
{
"type": "object",
"properties": {
"class": {
"type": "boolean"
},
"enum": {
"type": "boolean"
},
"function": {
"type": "boolean"
},
"import": {
"type": "boolean"
},
"interface": {
"type": "boolean"
},
"namespace": {
"type": "boolean"
},
"typeAlias": {
"type": "boolean"
},
"typeParameter": {
"type": "boolean"
},
"temporalDeadZone": {
"type": "boolean"
},
"underscore": {
"type": "boolean"
}
}
}
For more information see this page.
Missing semicolon Open
resolve(event)
- Read upRead up
- Exclude checks
Rule: semicolon
Enforces consistent semicolon usage at the end of every statement.
Notes
- Has Fix
Config
One of the following arguments must be provided:
-
"always"
enforces semicolons at the end of every statement. -
"never"
disallows semicolons at the end of every statement except for when they are necessary.
The following arguments may be optionally provided:
-
"ignore-interfaces"
skips checking semicolons at the end of interface members. -
"ignore-bound-class-methods"
skips checking semicolons at the end of bound class methods. -
"strict-bound-class-methods"
disables any special handling of bound class methods and treats them as any other assignment. This option overrides"ignore-bound-class-methods"
.
Examples
"semicolon": true,always
"semicolon": true,never
"semicolon": true,always,ignore-interfaces
"semicolon": true,always,ignore-bound-class-methods
Schema
{
"type": "array",
"items": [
{
"type": "string",
"enum": [
"always",
"never"
]
},
{
"type": "string",
"enum": [
"ignore-interfaces"
]
}
],
"additionalItems": false
}
For more information see this page.
comment must start with a space Open
if (records == null) return null; //TODO: throw?
- Read upRead up
- Exclude checks
Rule: comment-format
Enforces formatting rules for single-line comments.
Rationale
Helps maintain a consistent, readable style in your codebase.
Notes
- Has Fix
Config
Four arguments may be optionally provided:
-
"check-space"
requires that all single-line comments must begin with a space, as in// comment
- note that for comments starting with multiple slashes, e.g.
///
, leading slashes are ignored - TypeScript reference comments are ignored completely
- note that for comments starting with multiple slashes, e.g.
-
"check-lowercase"
requires that the first non-whitespace character of a comment must be lowercase, if applicable. -
"check-uppercase"
requires that the first non-whitespace character of a comment must be uppercase, if applicable. -
"allow-trailing-lowercase"
allows that only the first comment of a series of comments needs to be uppercase.- requires
"check-uppercase"
- comments must start at the same position
- requires
Exceptions to "check-lowercase"
or "check-uppercase"
can be managed with object that may be passed as last
argument.
One of two options can be provided in this object:
-
"ignore-words"
- array of strings - words that will be ignored at the beginning of the comment. -
"ignore-pattern"
- string - RegExp pattern that will be ignored at the beginning of the comment.
Examples
"comment-format": true,check-space,check-uppercase,allow-trailing-lowercase
"comment-format": true,check-lowercase,[object Object]
"comment-format": true,check-lowercase,[object Object]
Schema
{
"type": "array",
"items": {
"anyOf": [
{
"type": "string",
"enum": [
"check-space",
"check-lowercase",
"check-uppercase",
"allow-trailing-lowercase"
]
},
{
"type": "object",
"properties": {
"ignore-words": {
"type": "array",
"items": {
"type": "string"
}
},
"ignore-pattern": {
"type": "string"
}
},
"minProperties": 1,
"maxProperties": 1
}
]
},
"minLength": 1,
"maxLength": 5
}
For more information see this page.
Missing semicolon Open
if (!Array.isArray(records)) { records = [records] };
- Read upRead up
- Exclude checks
Rule: semicolon
Enforces consistent semicolon usage at the end of every statement.
Notes
- Has Fix
Config
One of the following arguments must be provided:
-
"always"
enforces semicolons at the end of every statement. -
"never"
disallows semicolons at the end of every statement except for when they are necessary.
The following arguments may be optionally provided:
-
"ignore-interfaces"
skips checking semicolons at the end of interface members. -
"ignore-bound-class-methods"
skips checking semicolons at the end of bound class methods. -
"strict-bound-class-methods"
disables any special handling of bound class methods and treats them as any other assignment. This option overrides"ignore-bound-class-methods"
.
Examples
"semicolon": true,always
"semicolon": true,never
"semicolon": true,always,ignore-interfaces
"semicolon": true,always,ignore-bound-class-methods
Schema
{
"type": "array",
"items": [
{
"type": "string",
"enum": [
"always",
"never"
]
},
{
"type": "string",
"enum": [
"ignore-interfaces"
]
}
],
"additionalItems": false
}
For more information see this page.
comment must start with a space Open
const isArray = Array.isArray(records);//DAMN TS COMPILER.
- Read upRead up
- Exclude checks
Rule: comment-format
Enforces formatting rules for single-line comments.
Rationale
Helps maintain a consistent, readable style in your codebase.
Notes
- Has Fix
Config
Four arguments may be optionally provided:
-
"check-space"
requires that all single-line comments must begin with a space, as in// comment
- note that for comments starting with multiple slashes, e.g.
///
, leading slashes are ignored - TypeScript reference comments are ignored completely
- note that for comments starting with multiple slashes, e.g.
-
"check-lowercase"
requires that the first non-whitespace character of a comment must be lowercase, if applicable. -
"check-uppercase"
requires that the first non-whitespace character of a comment must be uppercase, if applicable. -
"allow-trailing-lowercase"
allows that only the first comment of a series of comments needs to be uppercase.- requires
"check-uppercase"
- comments must start at the same position
- requires
Exceptions to "check-lowercase"
or "check-uppercase"
can be managed with object that may be passed as last
argument.
One of two options can be provided in this object:
-
"ignore-words"
- array of strings - words that will be ignored at the beginning of the comment. -
"ignore-pattern"
- string - RegExp pattern that will be ignored at the beginning of the comment.
Examples
"comment-format": true,check-space,check-uppercase,allow-trailing-lowercase
"comment-format": true,check-lowercase,[object Object]
"comment-format": true,check-lowercase,[object Object]
Schema
{
"type": "array",
"items": {
"anyOf": [
{
"type": "string",
"enum": [
"check-space",
"check-lowercase",
"check-uppercase",
"allow-trailing-lowercase"
]
},
{
"type": "object",
"properties": {
"ignore-words": {
"type": "array",
"items": {
"type": "string"
}
},
"ignore-pattern": {
"type": "string"
}
},
"minProperties": 1,
"maxProperties": 1
}
]
},
"minLength": 1,
"maxLength": 5
}
For more information see this page.
Identifier 'request' is never reassigned; use 'const' instead of 'var'. Open
var request = store
- Read upRead up
- Exclude checks
Rule: prefer-const
Requires that variable declarations use const
instead of let
and var
if possible.
If a variable is only assigned to once when it is declared, it should be declared using 'const'
Notes
- Has Fix
Config
An optional object containing the property "destructuring" with two possible values:
- "any" (default) - If any variable in destructuring can be const, this rule warns for those variables.
- "all" - Only warns if all variables in destructuring can be const.
Examples
"prefer-const": true
"prefer-const": true,[object Object]
Schema
{
"type": "object",
"properties": {
"destructuring": {
"type": "string",
"enum": [
"all",
"any"
]
}
}
}
For more information see this page.
comment must start with a space Open
//@ts-ignore
- Read upRead up
- Exclude checks
Rule: comment-format
Enforces formatting rules for single-line comments.
Rationale
Helps maintain a consistent, readable style in your codebase.
Notes
- Has Fix
Config
Four arguments may be optionally provided:
-
"check-space"
requires that all single-line comments must begin with a space, as in// comment
- note that for comments starting with multiple slashes, e.g.
///
, leading slashes are ignored - TypeScript reference comments are ignored completely
- note that for comments starting with multiple slashes, e.g.
-
"check-lowercase"
requires that the first non-whitespace character of a comment must be lowercase, if applicable. -
"check-uppercase"
requires that the first non-whitespace character of a comment must be uppercase, if applicable. -
"allow-trailing-lowercase"
allows that only the first comment of a series of comments needs to be uppercase.- requires
"check-uppercase"
- comments must start at the same position
- requires
Exceptions to "check-lowercase"
or "check-uppercase"
can be managed with object that may be passed as last
argument.
One of two options can be provided in this object:
-
"ignore-words"
- array of strings - words that will be ignored at the beginning of the comment. -
"ignore-pattern"
- string - RegExp pattern that will be ignored at the beginning of the comment.
Examples
"comment-format": true,check-space,check-uppercase,allow-trailing-lowercase
"comment-format": true,check-lowercase,[object Object]
"comment-format": true,check-lowercase,[object Object]
Schema
{
"type": "array",
"items": {
"anyOf": [
{
"type": "string",
"enum": [
"check-space",
"check-lowercase",
"check-uppercase",
"allow-trailing-lowercase"
]
},
{
"type": "object",
"properties": {
"ignore-words": {
"type": "array",
"items": {
"type": "string"
}
},
"ignore-pattern": {
"type": "string"
}
},
"minProperties": 1,
"maxProperties": 1
}
]
},
"minLength": 1,
"maxLength": 5
}
For more information see this page.
Shadowed name: 'resolve' Open
return new Promise<any>((resolve, reject) => {
- Read upRead up
- Exclude checks
Rule: no-shadowed-variable
Disallows shadowing variable declarations.
Rationale
When a variable in a local scope and a variable in the containing scope have the same name, shadowing occurs. Shadowing makes it impossible to access the variable in the containing scope and obscures to what value an identifier actually refers. Compare the following snippets:
const a = 'no shadow';
function print() {
console.log(a);
}
print(); // logs 'no shadow'.
const a = 'no shadow';
function print() {
const a = 'shadow'; // TSLint will complain here.
console.log(a);
}
print(); // logs 'shadow'.
ESLint has an equivalent rule. For more background information, refer to this MDN closure doc.
Config
You can optionally pass an object to disable checking for certain kinds of declarations.
Possible keys are "class"
, "enum"
, "function"
, "import"
, "interface"
, "namespace"
, "typeAlias"
and "typeParameter"
. You can also pass "underscore
" to ignore variable names that begin with _
.
Just set the value to false
for the check you want to disable.
All checks default to true
, i.e. are enabled by default.
Note that you cannot disable variables and parameters.
The option "temporalDeadZone"
defaults to true
which shows errors when shadowing block scoped declarations in their
temporal dead zone. When set to false
parameters, classes, enums and variables declared
with let
or const
are not considered shadowed if the shadowing occurs within their
temporal dead zone.
The following example shows how the "temporalDeadZone"
option changes the linting result:
function fn(value) {
if (value) {
const tmp = value; // no error on this line if "temporalDeadZone" is false
return tmp;
}
let tmp = undefined;
if (!value) {
const tmp = value; // this line always contains an error
return tmp;
}
}
Examples
"no-shadowed-variable": true
"no-shadowed-variable": true,[object Object]
Schema
{
"type": "object",
"properties": {
"class": {
"type": "boolean"
},
"enum": {
"type": "boolean"
},
"function": {
"type": "boolean"
},
"import": {
"type": "boolean"
},
"interface": {
"type": "boolean"
},
"namespace": {
"type": "boolean"
},
"typeAlias": {
"type": "boolean"
},
"typeParameter": {
"type": "boolean"
},
"temporalDeadZone": {
"type": "boolean"
},
"underscore": {
"type": "boolean"
}
}
}
For more information see this page.
Identifier 'myIndex' is never reassigned; use 'const' instead of 'var'. Open
var myIndex = store.index('id');
- Read upRead up
- Exclude checks
Rule: prefer-const
Requires that variable declarations use const
instead of let
and var
if possible.
If a variable is only assigned to once when it is declared, it should be declared using 'const'
Notes
- Has Fix
Config
An optional object containing the property "destructuring" with two possible values:
- "any" (default) - If any variable in destructuring can be const, this rule warns for those variables.
- "all" - Only warns if all variables in destructuring can be const.
Examples
"prefer-const": true
"prefer-const": true,[object Object]
Schema
{
"type": "object",
"properties": {
"destructuring": {
"type": "string",
"enum": [
"all",
"any"
]
}
}
}
For more information see this page.
Identifier 'getAllKeysRequest' is never reassigned; use 'const' instead of 'var'. Open
var getAllKeysRequest = myIndex.getAll();
- Read upRead up
- Exclude checks
Rule: prefer-const
Requires that variable declarations use const
instead of let
and var
if possible.
If a variable is only assigned to once when it is declared, it should be declared using 'const'
Notes
- Has Fix
Config
An optional object containing the property "destructuring" with two possible values:
- "any" (default) - If any variable in destructuring can be const, this rule warns for those variables.
- "all" - Only warns if all variables in destructuring can be const.
Examples
"prefer-const": true
"prefer-const": true,[object Object]
Schema
{
"type": "object",
"properties": {
"destructuring": {
"type": "string",
"enum": [
"all",
"any"
]
}
}
}
For more information see this page.
" should be ' Open
let objectStore = db.createObjectStore(this._objectStoreName, { keyPath: "id" });
- Read upRead up
- Exclude checks
Rule: quotemark
Enforces quote character for string literals.
Notes
- Has Fix
Config
Five arguments may be optionally provided:
-
"single"
enforces single quotes. -
"double"
enforces double quotes. -
"backtick"
enforces backticks. -
"jsx-single"
enforces single quotes for JSX attributes. -
"jsx-double"
enforces double quotes for JSX attributes. -
"avoid-template"
forbids single-line untagged template strings that do not contain string interpolations. Note that backticks may still be used if"avoid-escape"
is enabled and both single and double quotes are present in the string (the latter option takes precedence). -
"avoid-escape"
allows you to use the "other" quotemark in cases where escaping would normally be required. For example,[true, "double", "avoid-escape"]
would not report a failure on the string literal'Hello "World"'
.
Examples
"quotemark": true,single,avoid-escape,avoid-template
"quotemark": true,single,jsx-double
Schema
{
"type": "array",
"items": {
"type": "string",
"enum": [
"single",
"double",
"backtick",
"jsx-single",
"jsx-double",
"avoid-escape",
"avoid-template"
]
},
"minLength": 0,
"maxLength": 5
}
For more information see this page.
Forbidden 'var' keyword, use 'let' or 'const' instead Open
var getAllKeysRequest = myIndex.getAll();
- Read upRead up
- Exclude checks
Rule: no-var-keyword
Disallows usage of the var
keyword.
Use let
or const
instead.
Rationale
Declaring variables using var
has several edge case behaviors that make var
unsuitable for modern code.
Variables declared by var
have their parent function block as their scope, ignoring other control flow statements.
var
s have declaration "hoisting" (similar to function
s) and can appear to be used before declaration.
Variables declared by const
and let
instead have as their scope the block in which they are defined,
and are not allowed to used before declaration or be re-declared with another const
or let
.
Notes
- Has Fix
Config
Not configurable.
Examples
"no-var-keyword": true
For more information see this page.
Missing semicolon Open
}
- Read upRead up
- Exclude checks
Rule: semicolon
Enforces consistent semicolon usage at the end of every statement.
Notes
- Has Fix
Config
One of the following arguments must be provided:
-
"always"
enforces semicolons at the end of every statement. -
"never"
disallows semicolons at the end of every statement except for when they are necessary.
The following arguments may be optionally provided:
-
"ignore-interfaces"
skips checking semicolons at the end of interface members. -
"ignore-bound-class-methods"
skips checking semicolons at the end of bound class methods. -
"strict-bound-class-methods"
disables any special handling of bound class methods and treats them as any other assignment. This option overrides"ignore-bound-class-methods"
.
Examples
"semicolon": true,always
"semicolon": true,never
"semicolon": true,always,ignore-interfaces
"semicolon": true,always,ignore-bound-class-methods
Schema
{
"type": "array",
"items": [
{
"type": "string",
"enum": [
"always",
"never"
]
},
{
"type": "string",
"enum": [
"ignore-interfaces"
]
}
],
"additionalItems": false
}
For more information see this page.