Function open_chatroom
has 28 lines of code (exceeds 25 allowed). Consider refactoring. Open
var open_chatroom = function () {
var ws_scheme = (window.location.protocol === "https:") ? 'wss://' : 'ws://';
// Setup a websocket connection to the "chatroom", passing our worker_id and participant_id
chatroom_socket = new ReconnectingWebSocket(
ws_scheme + location.host + "/chat?channel=chatroom&worker_id=" + dallinger.identity.workerId + '&participant_id=' + dallinger.identity.participantId
- Create a ticketCreate a ticket
Function open_chatroom
has a Cognitive Complexity of 9 (exceeds 5 allowed). Consider refactoring. Open
var open_chatroom = function () {
var ws_scheme = (window.location.protocol === "https:") ? 'wss://' : 'ws://';
// Setup a websocket connection to the "chatroom", passing our worker_id and participant_id
chatroom_socket = new ReconnectingWebSocket(
ws_scheme + location.host + "/chat?channel=chatroom&worker_id=" + dallinger.identity.workerId + '&participant_id=' + dallinger.identity.participantId
- Read upRead up
- Create a ticketCreate a ticket
Cognitive Complexity
Cognitive Complexity is a measure of how difficult a unit of code is to intuitively understand. Unlike Cyclomatic Complexity, which determines how difficult your code will be to test, Cognitive Complexity tells you how difficult your code will be to read and comprehend.
A method's cognitive complexity is based on a few simple rules:
- Code is not considered more complex when it uses shorthand that the language provides for collapsing multiple statements into one
- Code is considered more complex for each "break in the linear flow of the code"
- Code is considered more complex when "flow breaking structures are nested"
Further reading
'create_agent' is assigned a value but never used. Open
var create_agent = function() {
- Read upRead up
- Create a ticketCreate a ticket
- Exclude checks
Disallow Unused Variables (no-unused-vars)
Variables that are declared and not used anywhere in the code are most likely an error due to incomplete refactoring. Such variables take up space in the code and can lead to confusion by readers.
Rule Details
This rule is aimed at eliminating unused variables, functions, and parameters of functions.
A variable is considered to be used if any of the following are true:
- It represents a function that is called (
doSomething()
) - It is read (
var y = x
) - It is passed into a function as an argument (
doSomething(x)
) - It is read inside of a function that is passed to another function (
doSomething(function() { foo(); })
)
A variable is not considered to be used if it is only ever assigned to (var x = 5
) or declared.
Examples of incorrect code for this rule:
/*eslint no-unused-vars: "error"*/
/*global some_unused_var*/
// It checks variables you have defined as global
some_unused_var = 42;
var x;
// Write-only variables are not considered as used.
var y = 10;
y = 5;
// A read for a modification of itself is not considered as used.
var z = 0;
z = z + 1;
// By default, unused arguments cause warnings.
(function(foo) {
return 5;
})();
// Unused recursive functions also cause warnings.
function fact(n) {
if (n < 2) return 1;
return n * fact(n - 1);
}
// When a function definition destructures an array, unused entries from the array also cause warnings.
function getY([x, y]) {
return y;
}
Examples of correct code for this rule:
/*eslint no-unused-vars: "error"*/
var x = 10;
alert(x);
// foo is considered used here
myFunc(function foo() {
// ...
}.bind(this));
(function(foo) {
return foo;
})();
var myFunc;
myFunc = setTimeout(function() {
// myFunc is considered used
myFunc();
}, 50);
// Only the second argument from the descructured array is used.
function getY([, y]) {
return y;
}
exported
In environments outside of CommonJS or ECMAScript modules, you may use var
to create a global variable that may be used by other scripts. You can use the /* exported variableName */
comment block to indicate that this variable is being exported and therefore should not be considered unused.
Note that /* exported */
has no effect for any of the following:
- when the environment is
node
orcommonjs
- when
parserOptions.sourceType
ismodule
- when
ecmaFeatures.globalReturn
istrue
The line comment // exported variableName
will not work as exported
is not line-specific.
Examples of correct code for /* exported variableName */
operation:
/* exported global_var */
var global_var = 42;
Options
This rule takes one argument which can be a string or an object. The string settings are the same as those of the vars
property (explained below).
By default this rule is enabled with all
option for variables and after-used
for arguments.
{
"rules": {
"no-unused-vars": ["error", { "vars": "all", "args": "after-used", "ignoreRestSiblings": false }]
}
}
vars
The vars
option has two settings:
-
all
checks all variables for usage, including those in the global scope. This is the default setting. -
local
checks only that locally-declared variables are used but will allow global variables to be unused.
vars: local
Examples of correct code for the { "vars": "local" }
option:
/*eslint no-unused-vars: ["error", { "vars": "local" }]*/
/*global some_unused_var */
some_unused_var = 42;
varsIgnorePattern
The varsIgnorePattern
option specifies exceptions not to check for usage: variables whose names match a regexp pattern. For example, variables whose names contain ignored
or Ignored
.
Examples of correct code for the { "varsIgnorePattern": "[iI]gnored" }
option:
/*eslint no-unused-vars: ["error", { "varsIgnorePattern": "[iI]gnored" }]*/
var firstVarIgnored = 1;
var secondVar = 2;
console.log(secondVar);
args
The args
option has three settings:
-
after-used
- only the last argument must be used. This allows you, for instance, to have two named parameters to a function and as long as you use the second argument, ESLint will not warn you about the first. This is the default setting. -
all
- all named arguments must be used. -
none
- do not check arguments.
args: after-used
Examples of incorrect code for the default { "args": "after-used" }
option:
/*eslint no-unused-vars: ["error", { "args": "after-used" }]*/
// 1 error
// "baz" is defined but never used
(function(foo, bar, baz) {
return bar;
})();
Examples of correct code for the default { "args": "after-used" }
option:
/*eslint no-unused-vars: ["error", {"args": "after-used"}]*/
(function(foo, bar, baz) {
return baz;
})();
args: all
Examples of incorrect code for the { "args": "all" }
option:
/*eslint no-unused-vars: ["error", { "args": "all" }]*/
// 2 errors
// "foo" is defined but never used
// "baz" is defined but never used
(function(foo, bar, baz) {
return bar;
})();
args: none
Examples of correct code for the { "args": "none" }
option:
/*eslint no-unused-vars: ["error", { "args": "none" }]*/
(function(foo, bar, baz) {
return bar;
})();
ignoreRestSiblings
The ignoreRestSiblings
option is a boolean (default: false
). Using a Rest Property it is possible to "omit" properties from an object, but by default the sibling properties are marked as "unused". With this option enabled the rest property's siblings are ignored.
Examples of correct code for the { "ignoreRestSiblings": true }
option:
/*eslint no-unused-vars: ["error", { "ignoreRestSiblings": true }]*/
// 'type' is ignored because it has a rest property sibling.
var { type, ...coords } = data;
argsIgnorePattern
The argsIgnorePattern
option specifies exceptions not to check for usage: arguments whose names match a regexp pattern. For example, variables whose names begin with an underscore.
Examples of correct code for the { "argsIgnorePattern": "^_" }
option:
/*eslint no-unused-vars: ["error", { "argsIgnorePattern": "^_" }]*/
function foo(x, _y) {
return x + 1;
}
foo();
caughtErrors
The caughtErrors
option is used for catch
block arguments validation.
It has two settings:
-
none
- do not check error objects. This is the default setting. -
all
- all named arguments must be used.
caughtErrors: none
Not specifying this rule is equivalent of assigning it to none
.
Examples of correct code for the { "caughtErrors": "none" }
option:
/*eslint no-unused-vars: ["error", { "caughtErrors": "none" }]*/
try {
//...
} catch (err) {
console.error("errors");
}
caughtErrors: all
Examples of incorrect code for the { "caughtErrors": "all" }
option:
/*eslint no-unused-vars: ["error", { "caughtErrors": "all" }]*/
// 1 error
// "err" is defined but never used
try {
//...
} catch (err) {
console.error("errors");
}
caughtErrorsIgnorePattern
The caughtErrorsIgnorePattern
option specifies exceptions not to check for usage: catch arguments whose names match a regexp pattern. For example, variables whose names begin with a string 'ignore'.
Examples of correct code for the { "caughtErrorsIgnorePattern": "^ignore" }
option:
/*eslint no-unused-vars: ["error", { "caughtErrorsIgnorePattern": "^ignore" }]*/
try {
//...
} catch (ignoreErr) {
console.error("errors");
}
When Not To Use It
If you don't want to be notified about unused variables or function arguments, you can safely turn this rule off. Source: http://eslint.org/docs/rules/
Expected '===' and instead saw '=='. Open
if (type == 'message') {
- Read upRead up
- Create a ticketCreate a ticket
- Exclude checks
Require === and !== (eqeqeq)
It is considered good practice to use the type-safe equality operators ===
and !==
instead of their regular counterparts ==
and !=
.
The reason for this is that ==
and !=
do type coercion which follows the rather obscure Abstract Equality Comparison Algorithm.
For instance, the following statements are all considered true
:
[] == false
[] == ![]
3 == "03"
If one of those occurs in an innocent-looking statement such as a == b
the actual problem is very difficult to spot.
Rule Details
This rule is aimed at eliminating the type-unsafe equality operators.
Examples of incorrect code for this rule:
/*eslint eqeqeq: "error"*/
if (x == 42) { }
if ("" == text) { }
if (obj.getStuff() != undefined) { }
The --fix
option on the command line automatically fixes some problems reported by this rule. A problem is only fixed if one of the operands is a typeof
expression, or if both operands are literals with the same type.
Options
always
The "always"
option (default) enforces the use of ===
and !==
in every situation (except when you opt-in to more specific handling of null
[see below]).
Examples of incorrect code for the "always"
option:
/*eslint eqeqeq: ["error", "always"]*/
a == b
foo == true
bananas != 1
value == undefined
typeof foo == 'undefined'
'hello' != 'world'
0 == 0
true == true
foo == null
Examples of correct code for the "always"
option:
/*eslint eqeqeq: ["error", "always"]*/
a === b
foo === true
bananas !== 1
value === undefined
typeof foo === 'undefined'
'hello' !== 'world'
0 === 0
true === true
foo === null
This rule optionally takes a second argument, which should be an object with the following supported properties:
-
"null"
: Customize how this rule treatsnull
literals. Possible values:-
always
(default) - Always use === or !==. -
never
- Never use === or !== withnull
. -
ignore
- Do not apply this rule tonull
.
-
smart
The "smart"
option enforces the use of ===
and !==
except for these cases:
- Comparing two literal values
- Evaluating the value of
typeof
- Comparing against
null
Examples of incorrect code for the "smart"
option:
/*eslint eqeqeq: ["error", "smart"]*/
// comparing two variables requires ===
a == b
// only one side is a literal
foo == true
bananas != 1
// comparing to undefined requires ===
value == undefined
Examples of correct code for the "smart"
option:
/*eslint eqeqeq: ["error", "smart"]*/
typeof foo == 'undefined'
'hello' != 'world'
0 == 0
true == true
foo == null
allow-null
Deprecated: Instead of using this option use "always" and pass a "null" option property with value "ignore". This will tell eslint to always enforce strict equality except when comparing with the null
literal.
["error", "always", {"null": "ignore"}]
When Not To Use It
If you don't want to enforce a style for using equality operators, then it's safe to disable this rule. Source: http://eslint.org/docs/rules/
Expected '===' and instead saw '=='. Open
if (data.action == 'finish') {
- Read upRead up
- Create a ticketCreate a ticket
- Exclude checks
Require === and !== (eqeqeq)
It is considered good practice to use the type-safe equality operators ===
and !==
instead of their regular counterparts ==
and !=
.
The reason for this is that ==
and !=
do type coercion which follows the rather obscure Abstract Equality Comparison Algorithm.
For instance, the following statements are all considered true
:
[] == false
[] == ![]
3 == "03"
If one of those occurs in an innocent-looking statement such as a == b
the actual problem is very difficult to spot.
Rule Details
This rule is aimed at eliminating the type-unsafe equality operators.
Examples of incorrect code for this rule:
/*eslint eqeqeq: "error"*/
if (x == 42) { }
if ("" == text) { }
if (obj.getStuff() != undefined) { }
The --fix
option on the command line automatically fixes some problems reported by this rule. A problem is only fixed if one of the operands is a typeof
expression, or if both operands are literals with the same type.
Options
always
The "always"
option (default) enforces the use of ===
and !==
in every situation (except when you opt-in to more specific handling of null
[see below]).
Examples of incorrect code for the "always"
option:
/*eslint eqeqeq: ["error", "always"]*/
a == b
foo == true
bananas != 1
value == undefined
typeof foo == 'undefined'
'hello' != 'world'
0 == 0
true == true
foo == null
Examples of correct code for the "always"
option:
/*eslint eqeqeq: ["error", "always"]*/
a === b
foo === true
bananas !== 1
value === undefined
typeof foo === 'undefined'
'hello' !== 'world'
0 === 0
true === true
foo === null
This rule optionally takes a second argument, which should be an object with the following supported properties:
-
"null"
: Customize how this rule treatsnull
literals. Possible values:-
always
(default) - Always use === or !==. -
never
- Never use === or !== withnull
. -
ignore
- Do not apply this rule tonull
.
-
smart
The "smart"
option enforces the use of ===
and !==
except for these cases:
- Comparing two literal values
- Evaluating the value of
typeof
- Comparing against
null
Examples of incorrect code for the "smart"
option:
/*eslint eqeqeq: ["error", "smart"]*/
// comparing two variables requires ===
a == b
// only one side is a literal
foo == true
bananas != 1
// comparing to undefined requires ===
value == undefined
Examples of correct code for the "smart"
option:
/*eslint eqeqeq: ["error", "smart"]*/
typeof foo == 'undefined'
'hello' != 'world'
0 == 0
true == true
foo == null
allow-null
Deprecated: Instead of using this option use "always" and pass a "null" option property with value "ignore". This will tell eslint to always enforce strict equality except when comparing with the null
literal.
["error", "always", {"null": "ignore"}]
When Not To Use It
If you don't want to enforce a style for using equality operators, then it's safe to disable this rule. Source: http://eslint.org/docs/rules/
Unexpected trailing comma. Open
'node_id': my_node_id,
- Read upRead up
- Create a ticketCreate a ticket
- 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/
Expected '===' and instead saw '=='. Open
} else if (type == 'log') {
- Read upRead up
- Create a ticketCreate a ticket
- Exclude checks
Require === and !== (eqeqeq)
It is considered good practice to use the type-safe equality operators ===
and !==
instead of their regular counterparts ==
and !=
.
The reason for this is that ==
and !=
do type coercion which follows the rather obscure Abstract Equality Comparison Algorithm.
For instance, the following statements are all considered true
:
[] == false
[] == ![]
3 == "03"
If one of those occurs in an innocent-looking statement such as a == b
the actual problem is very difficult to spot.
Rule Details
This rule is aimed at eliminating the type-unsafe equality operators.
Examples of incorrect code for this rule:
/*eslint eqeqeq: "error"*/
if (x == 42) { }
if ("" == text) { }
if (obj.getStuff() != undefined) { }
The --fix
option on the command line automatically fixes some problems reported by this rule. A problem is only fixed if one of the operands is a typeof
expression, or if both operands are literals with the same type.
Options
always
The "always"
option (default) enforces the use of ===
and !==
in every situation (except when you opt-in to more specific handling of null
[see below]).
Examples of incorrect code for the "always"
option:
/*eslint eqeqeq: ["error", "always"]*/
a == b
foo == true
bananas != 1
value == undefined
typeof foo == 'undefined'
'hello' != 'world'
0 == 0
true == true
foo == null
Examples of correct code for the "always"
option:
/*eslint eqeqeq: ["error", "always"]*/
a === b
foo === true
bananas !== 1
value === undefined
typeof foo === 'undefined'
'hello' !== 'world'
0 === 0
true === true
foo === null
This rule optionally takes a second argument, which should be an object with the following supported properties:
-
"null"
: Customize how this rule treatsnull
literals. Possible values:-
always
(default) - Always use === or !==. -
never
- Never use === or !== withnull
. -
ignore
- Do not apply this rule tonull
.
-
smart
The "smart"
option enforces the use of ===
and !==
except for these cases:
- Comparing two literal values
- Evaluating the value of
typeof
- Comparing against
null
Examples of incorrect code for the "smart"
option:
/*eslint eqeqeq: ["error", "smart"]*/
// comparing two variables requires ===
a == b
// only one side is a literal
foo == true
bananas != 1
// comparing to undefined requires ===
value == undefined
Examples of correct code for the "smart"
option:
/*eslint eqeqeq: ["error", "smart"]*/
typeof foo == 'undefined'
'hello' != 'world'
0 == 0
true == true
foo == null
allow-null
Deprecated: Instead of using this option use "always" and pass a "null" option property with value "ignore". This will tell eslint to always enforce strict equality except when comparing with the null
literal.
["error", "always", {"null": "ignore"}]
When Not To Use It
If you don't want to enforce a style for using equality operators, then it's safe to disable this rule. Source: http://eslint.org/docs/rules/
Unexpected trailing comma. Open
'node_id': my_node_id,
- Read upRead up
- Create a ticketCreate a ticket
- 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 trailing comma. Open
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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/
Expected indentation of 4 spaces but found 6. Open
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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/
Identical blocks of code found in 2 locations. Consider refactoring. Open
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send_message();
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Duplicated Code
Duplicated code can lead to software that is hard to understand and difficult to change. The Don't Repeat Yourself (DRY) principle states:
Every piece of knowledge must have a single, unambiguous, authoritative representation within a system.
When you violate DRY, bugs and maintenance problems are sure to follow. Duplicated code has a tendency to both continue to replicate and also to diverge (leaving bugs as two similar implementations differ in subtle ways).
Tuning
This issue has a mass of 113.
We set useful threshold defaults for the languages we support but you may want to adjust these settings based on your project guidelines.
The threshold configuration represents the minimum mass a code block must have to be analyzed for duplication. The lower the threshold, the more fine-grained the comparison.
If the engine is too easily reporting duplication, try raising the threshold. If you suspect that the engine isn't catching enough duplication, try lowering the threshold. The best setting tends to differ from language to language.
See codeclimate-duplication
's documentation for more information about tuning the mass threshold in your .codeclimate.yml
.
Refactorings
- Extract Method
- Extract Class
- Form Template Method
- Introduce Null Object
- Pull Up Method
- Pull Up Field
- Substitute Algorithm
Further Reading
- Don't Repeat Yourself on the C2 Wiki
- Duplicated Code on SourceMaking
- Refactoring: Improving the Design of Existing Code by Martin Fowler. Duplicated Code, p76
Identical blocks of code found in 2 locations. Consider refactoring. Open
$(document).keypress(function (e) {
if (e.which === 13) {
console.log("enter!");
$("#send-message").click();
return false;
- Read upRead up
- Create a ticketCreate a ticket
Duplicated Code
Duplicated code can lead to software that is hard to understand and difficult to change. The Don't Repeat Yourself (DRY) principle states:
Every piece of knowledge must have a single, unambiguous, authoritative representation within a system.
When you violate DRY, bugs and maintenance problems are sure to follow. Duplicated code has a tendency to both continue to replicate and also to diverge (leaving bugs as two similar implementations differ in subtle ways).
Tuning
This issue has a mass of 64.
We set useful threshold defaults for the languages we support but you may want to adjust these settings based on your project guidelines.
The threshold configuration represents the minimum mass a code block must have to be analyzed for duplication. The lower the threshold, the more fine-grained the comparison.
If the engine is too easily reporting duplication, try raising the threshold. If you suspect that the engine isn't catching enough duplication, try lowering the threshold. The best setting tends to differ from language to language.
See codeclimate-duplication
's documentation for more information about tuning the mass threshold in your .codeclimate.yml
.
Refactorings
- Extract Method
- Extract Class
- Form Template Method
- Introduce Null Object
- Pull Up Method
- Pull Up Field
- Substitute Algorithm
Further Reading
- Don't Repeat Yourself on the C2 Wiki
- Duplicated Code on SourceMaking
- Refactoring: Improving the Design of Existing Code by Martin Fowler. Duplicated Code, p76
Similar blocks of code found in 2 locations. Consider refactoring. Open
chatroom_socket = new ReconnectingWebSocket(
ws_scheme + location.host + "/chat?channel=chatroom&worker_id=" + dallinger.identity.workerId + '&participant_id=' + dallinger.identity.participantId
);
- Read upRead up
- Create a ticketCreate a ticket
Duplicated Code
Duplicated code can lead to software that is hard to understand and difficult to change. The Don't Repeat Yourself (DRY) principle states:
Every piece of knowledge must have a single, unambiguous, authoritative representation within a system.
When you violate DRY, bugs and maintenance problems are sure to follow. Duplicated code has a tendency to both continue to replicate and also to diverge (leaving bugs as two similar implementations differ in subtle ways).
Tuning
This issue has a mass of 45.
We set useful threshold defaults for the languages we support but you may want to adjust these settings based on your project guidelines.
The threshold configuration represents the minimum mass a code block must have to be analyzed for duplication. The lower the threshold, the more fine-grained the comparison.
If the engine is too easily reporting duplication, try raising the threshold. If you suspect that the engine isn't catching enough duplication, try lowering the threshold. The best setting tends to differ from language to language.
See codeclimate-duplication
's documentation for more information about tuning the mass threshold in your .codeclimate.yml
.
Refactorings
- Extract Method
- Extract Class
- Form Template Method
- Introduce Null Object
- Pull Up Method
- Pull Up Field
- Substitute Algorithm
Further Reading
- Don't Repeat Yourself on the C2 Wiki
- Duplicated Code on SourceMaking
- Refactoring: Improving the Design of Existing Code by Martin Fowler. Duplicated Code, p76