function _success(position) {

Close

disallow dangling underscores in identifiers (no-underscore-dangle)

As far as naming conventions for identifiers go, dangling underscores may be the most polarizing in JavaScript. Dangling underscores are underscores at either the beginning or end of an identifier, such as:

var _foo;

There is actually a long history of using dangling underscores to indicate "private" members of objects in JavaScript (though JavaScript doesn't have truly private members, this convention served as a warning). This began with SpiderMonkey adding nonstandard methods such as __defineGetter__(). The intent with the underscores was to make it obvious that this method was special in some way. Since that time, using a single underscore prefix has become popular as a way to indicate "private" members of objects.

Whether or not you choose to allow dangling underscores in identifiers is purely a convention and has no effect on performance, readability, or complexity. It's purely a preference.

Rule Details

This rule disallows dangling underscores in identifiers.

Examples of incorrect code for this rule:

/*eslint no-underscore-dangle: "error"*/

var foo_;
var __proto__ = {};
foo._bar();

Examples of correct code for this rule:

/*eslint no-underscore-dangle: "error"*/

var _ = require('underscore');
var obj = _.contains(items, item);
obj.__proto__ = {};
var file = __filename;

Options

This rule has an object option:

• "allow" allows specified identifiers to have dangling underscores
• "allowAfterThis": false (default) disallows dangling underscores in members of the this object
• "allowAfterSuper": false (default) disallows dangling underscores in members of the super object

allow

Examples of additional correct code for this rule with the { "allow": ["foo_", "_bar"] } option:

/*eslint no-underscore-dangle: ["error", { "allow": ["foo_", "_bar"] }]*/

var foo_;
foo._bar();

allowAfterThis

Examples of correct code for this rule with the { "allowAfterThis": true } option:

/*eslint no-underscore-dangle: ["error", { "allowAfterThis": true }]*/

var a = this.foo_;
this._bar();

allowAfterSuper

Examples of correct code for this rule with the { "allowAfterSuper": true } option:

/*eslint no-underscore-dangle: ["error", { "allowAfterSuper": true }]*/

var a = super.foo_;
super._bar();

When Not To Use It

If you want to allow dangling underscores in identifiers, then you can safely turn this rule off. Source: http://eslint.org/docs/rules/

  switch(error.code) {

Close

Require Default Case in Switch Statements (default-case)

Some code conventions require that all switch statements have a default case, even if the default case is empty, such as:

switch (foo) {
    case 1:
        doSomething();
        break;

    case 2:
        doSomething();
        break;

    default:
        // do nothing
}

The thinking is that it's better to always explicitly state what the default behavior should be so that it's clear whether or not the developer forgot to include the default behavior by mistake.

Other code conventions allow you to skip the default case so long as there is a comment indicating the omission is intentional, such as:

switch (foo) {
    case 1:
        doSomething();
        break;

    case 2:
        doSomething();
        break;

    // no default
}

Once again, the intent here is to show that the developer intended for there to be no default behavior.

Rule Details

This rule aims to require default case in switch statements. You may optionally include a // no default after the last case if there is no default case. The comment may be in any desired case, such as // No Default.

Examples of incorrect code for this rule:

/*eslint default-case: "error"*/

switch (a) {
    case 1:
        /* code */
        break;
}

Examples of correct code for this rule:

/*eslint default-case: "error"*/

switch (a) {
    case 1:
        /* code */
        break;

    default:
        /* code */
        break;
}


switch (a) {
    case 1:
        /* code */
        break;

    // no default
}

switch (a) {
    case 1:
        /* code */
        break;

    // No Default
}

Options

This rule accepts a single options argument:

• Set the commentPattern option to a regular expression string to change the default /^no default$/i comment test pattern

commentPattern

Examples of correct code for the { "commentPattern": "^skip\\sdefault" } option:

/*eslint default-case: ["error", { "commentPattern": "^skip\\sdefault" }]*/

switch(a) {
    case 1:
        /* code */
        break;

    // skip default
}

switch(a) {
    case 1:
        /* code */
        break;

    // skip default case
}

When Not To Use It

If you don't want to enforce a default case for switch statements, you can safely disable this rule.

Related Rules

• [no-fallthrough](no-fallthrough.md) Source: http://eslint.org/docs/rules/

var _infoBoxDelay;

Close

disallow dangling underscores in identifiers (no-underscore-dangle)

As far as naming conventions for identifiers go, dangling underscores may be the most polarizing in JavaScript. Dangling underscores are underscores at either the beginning or end of an identifier, such as:

var _foo;

There is actually a long history of using dangling underscores to indicate "private" members of objects in JavaScript (though JavaScript doesn't have truly private members, this convention served as a warning). This began with SpiderMonkey adding nonstandard methods such as __defineGetter__(). The intent with the underscores was to make it obvious that this method was special in some way. Since that time, using a single underscore prefix has become popular as a way to indicate "private" members of objects.

Whether or not you choose to allow dangling underscores in identifiers is purely a convention and has no effect on performance, readability, or complexity. It's purely a preference.

Rule Details

This rule disallows dangling underscores in identifiers.

Examples of incorrect code for this rule:

/*eslint no-underscore-dangle: "error"*/

var foo_;
var __proto__ = {};
foo._bar();

Examples of correct code for this rule:

/*eslint no-underscore-dangle: "error"*/

var _ = require('underscore');
var obj = _.contains(items, item);
obj.__proto__ = {};
var file = __filename;

Options

This rule has an object option:

• "allow" allows specified identifiers to have dangling underscores
• "allowAfterThis": false (default) disallows dangling underscores in members of the this object
• "allowAfterSuper": false (default) disallows dangling underscores in members of the super object

allow

Examples of additional correct code for this rule with the { "allow": ["foo_", "_bar"] } option:

/*eslint no-underscore-dangle: ["error", { "allow": ["foo_", "_bar"] }]*/

var foo_;
foo._bar();

allowAfterThis

Examples of correct code for this rule with the { "allowAfterThis": true } option:

/*eslint no-underscore-dangle: ["error", { "allowAfterThis": true }]*/

var a = this.foo_;
this._bar();

allowAfterSuper

Examples of correct code for this rule with the { "allowAfterSuper": true } option:

/*eslint no-underscore-dangle: ["error", { "allowAfterSuper": true }]*/

var a = super.foo_;
super._bar();

When Not To Use It

If you want to allow dangling underscores in identifiers, then you can safely turn this rule off. Source: http://eslint.org/docs/rules/

    var buttonClose = contentDiv.querySelector('.button-close');

Close

require let or const instead of var (no-var)

ECMAScript 6 allows programmers to create variables with block scope instead of function scope using the let and const keywords. Block scope is common in many other programming languages and helps programmers avoid mistakes such as:

var count = people.length;
var enoughFood = count > sandwiches.length;

if (enoughFood) {
    var count = sandwiches.length; // accidentally overriding the count variable
    console.log("We have " + count + " sandwiches for everyone. Plenty for all!");
}

// our count variable is no longer accurate
console.log("We have " + count + " people and " + sandwiches.length + " sandwiches!");

Rule Details

This rule is aimed at discouraging the use of var and encouraging the use of const or let instead.

Examples

Examples of incorrect code for this rule:

/*eslint no-var: "error"*/

var x = "y";
var CONFIG = {};

Examples of correct code for this rule:

/*eslint no-var: "error"*/
/*eslint-env es6*/

let x = "y";
const CONFIG = {};

When Not To Use It

In addition to non-ES6 environments, existing JavaScript projects that are beginning to introduce ES6 into their codebase may not want to apply this rule if the cost of migrating from var to let is too costly. Source: http://eslint.org/docs/rules/

  updateInfoBoxState:updateInfoBoxState,

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enforce consistent spacing between keys and values in object literal properties (key-spacing)

This rule enforces spacing around the colon in object literal properties. It can verify each property individually, or it can ensure horizontal alignment of adjacent properties in an object literal.

Rule Details

This rule enforces consistent spacing between keys and values in object literal properties. In the case of long lines, it is acceptable to add a new line wherever whitespace is allowed.

Options

This rule has an object option:

• "beforeColon": false (default) disallows spaces between the key and the colon in object literals.
• "beforeColon": true requires at least one space between the key and the colon in object literals.
• "afterColon": true (default) requires at least one space between the colon and the value in object literals.
• "afterColon": false disallows spaces between the colon and the value in object literals.
• "mode": "strict" (default) enforces exactly one space before or after colons in object literals.
• "mode": "minimum" enforces one or more spaces before or after colons in object literals.
• "align": "value" enforces horizontal alignment of values in object literals.
• "align": "colon" enforces horizontal alignment of both colons and values in object literals.
• "align" with an object value allows for fine-grained spacing when values are being aligned in object literals.
• "singleLine" specifies a spacing style for single-line object literals.
• "multiLine" specifies a spacing style for multi-line object literals.

Please note that you can either use the top-level options or the grouped options (singleLine and multiLine) but not both.

beforeColon

Examples of incorrect code for this rule with the default { "beforeColon": false } option:

/*eslint key-spacing: ["error", { "beforeColon": false }]*/

var obj = { "foo" : 42 };

Examples of correct code for this rule with the default { "beforeColon": false } option:

/*eslint key-spacing: ["error", { "beforeColon": false }]*/

var obj = { "foo": 42 };

Examples of incorrect code for this rule with the { "beforeColon": true } option:

/*eslint key-spacing: ["error", { "beforeColon": true }]*/

var obj = { "foo": 42 };

Examples of correct code for this rule with the { "beforeColon": true } option:

/*eslint key-spacing: ["error", { "beforeColon": true }]*/

var obj = { "foo" : 42 };

afterColon

Examples of incorrect code for this rule with the default { "afterColon": true } option:

/*eslint key-spacing: ["error", { "afterColon": true }]*/

var obj = { "foo":42 };

Examples of correct code for this rule with the default { "afterColon": true } option:

/*eslint key-spacing: ["error", { "afterColon": true }]*/

var obj = { "foo": 42 };

Examples of incorrect code for this rule with the { "afterColon": false } option:

/*eslint key-spacing: ["error", { "afterColon": false }]*/

var obj = { "foo": 42 };

Examples of correct code for this rule with the { "afterColon": false } option:

/*eslint key-spacing: ["error", { "afterColon": false }]*/

var obj = { "foo":42 };

mode

Examples of incorrect code for this rule with the default { "mode": "strict" } option:

/*eslint key-spacing: ["error", { "mode": "strict" }]*/

call({
    foobar: 42,
    bat:    2 * 2
});

Examples of correct code for this rule with the default { "mode": "strict" } option:

/*eslint key-spacing: ["error", { "mode": "strict" }]*/

call({
    foobar: 42,
    bat: 2 * 2
});

Examples of correct code for this rule with the { "mode": "minimum" } option:

/*eslint key-spacing: ["error", { "mode": "minimum" }]*/

call({
    foobar: 42,
    bat:    2 * 2
});

align

Examples of incorrect code for this rule with the { "align": "value" } option:

/*eslint key-spacing: ["error", { "align": "value" }]*/

var obj = {
    a: value,
    bcde:  42,
    fg :   foo()
};

Examples of correct code for this rule with the { "align": "value" } option:

/*eslint key-spacing: ["error", { "align": "value" }]*/

var obj = {
    a:    value,
    bcde: 42,

    fg: foo(),
    h:  function() {
        return this.a;
    },
    ijkl: 'Non-consecutive lines form a new group'
};

var obj = { a: "foo", longPropertyName: "bar" };

Examples of incorrect code for this rule with the { "align": "colon" } option:

/*eslint key-spacing: ["error", { "align": "colon" }]*/

call({
    foobar: 42,
    bat:    2 * 2
});

Examples of correct code for this rule with the { "align": "colon" } option:

/*eslint key-spacing: ["error", { "align": "colon" }]*/

call({
    foobar: 42,
    bat   : 2 * 2
});

align

The align option can take additional configuration through the beforeColon, afterColon, mode, and on options.

If align is defined as an object, but not all of the parameters are provided, undefined parameters will default to the following:

// Defaults
align: {
    "beforeColon": false,
    "afterColon": true,
    "on": "colon",
    "mode": "strict"
}

Examples of correct code for this rule with sample { "align": { } } options:

/*eslint key-spacing: ["error", {
    "align": {
        "beforeColon": true,
        "afterColon": true,
        "on": "colon"
    }
}]*/

var obj = {
    "one"   : 1,
    "seven" : 7
}

/*eslint key-spacing: ["error", {
    "align": {
        "beforeColon": false,
        "afterColon": false,
        "on": "value"
    }
}]*/

var obj = {
    "one":  1,
    "seven":7
}

align and multiLine

The multiLine and align options can differ, which allows for fine-tuned control over the key-spacing of your files. align will not inherit from multiLine if align is configured as an object.

multiLine is used any time an object literal spans multiple lines. The align configuration is used when there is a group of properties in the same object. For example:

var myObj = {
  key1: 1, // uses multiLine

  key2: 2, // uses align (when defined)
  key3: 3, // uses align (when defined)

  key4: 4 // uses multiLine
}

Examples of incorrect code for this rule with sample { "align": { }, "multiLine": { } } options:

/*eslint key-spacing: ["error", {
    "multiLine": {
        "beforeColon": false,
        "afterColon":true
    },
    "align": {
        "beforeColon": true,
        "afterColon": true,
        "on": "colon"
    }
}]*/

var obj = {
    "myObjectFunction": function() {
        // Do something
    },
    "one"             : 1,
    "seven"           : 7
}

Examples of correct code for this rule with sample { "align": { }, "multiLine": { } } options:

/*eslint key-spacing: ["error", {
    "multiLine": {
        "beforeColon": false,
        "afterColon": true

    },
    "align": {
        "beforeColon": true,
        "afterColon": true,
        "on": "colon"
    }
}]*/

var obj = {
    "myObjectFunction": function() {
        // Do something
        //
    }, // These are two separate groups, so no alignment between `myObjectFuction` and `one`
    "one"   : 1,
    "seven" : 7 // `one` and `seven` are in their own group, and therefore aligned
}

singleLine and multiLine

Examples of correct code for this rule with sample { "singleLine": { }, "multiLine": { } } options:

/*eslint "key-spacing": [2, {
    "singleLine": {
        "beforeColon": false,
        "afterColon": true
    },
    "multiLine": {
        "beforeColon": true,
        "afterColon": true,
        "align": "colon"
    }
}]*/
var obj = { one: 1, "two": 2, three: 3 };
var obj2 = {
    "two" : 2,
    three : 3
};

When Not To Use It

If you have another convention for property spacing that might not be consistent with the available options, or if you want to permit multiple styles concurrently you can safely disable this rule. Source: http://eslint.org/docs/rules/

  registerInfoBoxEvents:registerInfoBoxEvents,

Close

Require Object Literal Shorthand Syntax (object-shorthand)

EcmaScript 6 provides a concise form for defining object literal methods and properties. This syntax can make defining complex object literals much cleaner.

Here are a few common examples using the ES5 syntax:

// properties
var foo = {
    x: x,
    y: y,
    z: z,
};

// methods
var foo = {
    a: function() {},
    b: function() {}
};

Now here are ES6 equivalents:

/*eslint-env es6*/

// properties
var foo = {x, y, z};

// methods
var foo = {
    a() {},
    b() {}
};

Rule Details

This rule enforces the use of the shorthand syntax. This applies to all methods (including generators) defined in object literals and any properties defined where the key name matches name of the assigned variable.

Each of the following properties would warn:

/*eslint object-shorthand: "error"*/
/*eslint-env es6*/

var foo = {
    w: function() {},
    x: function *() {},
    [y]: function() {},
    z: z
};

In that case the expected syntax would have been:

/*eslint object-shorthand: "error"*/
/*eslint-env es6*/

var foo = {
    w() {},
    *x() {},
    [y]() {},
    z
};

This rule does not flag arrow functions inside of object literals. The following will not warn:

/*eslint object-shorthand: "error"*/
/*eslint-env es6*/

var foo = {
    x: (y) => y
};

Options

The rule takes an option which specifies when it should be applied. It can be set to one of the following values:

• "always" (default) expects that the shorthand will be used whenever possible.
• "methods" ensures the method shorthand is used (also applies to generators).
• "properties" ensures the property shorthand is used (where the key and variable name match).
• "never" ensures that no property or method shorthand is used in any object literal.
• "consistent" ensures that either all shorthand or all longform will be used in an object literal.
• "consistent-as-needed" ensures that either all shorthand or all longform will be used in an object literal, but ensures all shorthand whenever possible.

You can set the option in configuration like this:

{
    "object-shorthand": ["error", "always"]
}

Additionally, the rule takes an optional object configuration:

• "avoidQuotes": true indicates that longform syntax is preferred whenever the object key is a string literal (default: false). Note that this option can only be enabled when the string option is set to "always", "methods", or "properties".
• "ignoreConstructors": true can be used to prevent the rule from reporting errors for constructor functions. (By default, the rule treats constructors the same way as other functions.) Note that this option can only be enabled when the string option is set to "always" or "methods".
• "avoidExplicitReturnArrows": true indicates that methods are preferred over explicit-return arrow functions for function properties. (By default, the rule allows either of these.) Note that this option can only be enabled when the string option is set to "always" or "methods".

avoidQuotes

{
    "object-shorthand": ["error", "always", { "avoidQuotes": true }]
}

Example of incorrect code for this rule with the "always", { "avoidQuotes": true } option:

/*eslint object-shorthand: ["error", "always", { "avoidQuotes": true }]*/
/*eslint-env es6*/

var foo = {
    "bar-baz"() {}
};

Example of correct code for this rule with the "always", { "avoidQuotes": true } option:

/*eslint object-shorthand: ["error", "always", { "avoidQuotes": true }]*/
/*eslint-env es6*/

var foo = {
    "bar-baz": function() {},
    "qux": qux
};

ignoreConstructors

{
    "object-shorthand": ["error", "always", { "ignoreConstructors": true }]
}

Example of correct code for this rule with the "always", { "ignoreConstructors": true } option:

/*eslint object-shorthand: ["error", "always", { "ignoreConstructors": true }]*/
/*eslint-env es6*/

var foo = {
    ConstructorFunction: function() {}
};

avoidExplicitReturnArrows

{
    "object-shorthand": ["error", "always", { "avoidExplicitReturnArrows": true }]
}

Example of incorrect code for this rule with the "always", { "avoidExplicitReturnArrows": true } option:

/*eslint object-shorthand: ["error", "always", { "avoidExplicitReturnArrows": true }]*/
/*eslint-env es6*/

var foo = {
  foo: (bar, baz) => {
    return bar + baz;
  },

  qux: (foobar) => {
    return foobar * 2;
  }
};

Example of correct code for this rule with the "always", { "avoidExplicitReturnArrows": true } option:

/*eslint object-shorthand: ["error", "always", { "avoidExplicitReturnArrows": true }]*/
/*eslint-env es6*/

var foo = {
  foo(bar, baz) {
    return bar + baz;
  },

  qux: foobar => foobar * 2
};

Example of incorrect code for this rule with the "consistent" option:

/*eslint object-shorthand: [2, "consistent"]*/
/*eslint-env es6*/

var foo = {
    a,
    b: "foo",
};

Examples of correct code for this rule with the "consistent" option:

/*eslint object-shorthand: [2, "consistent"]*/
/*eslint-env es6*/

var foo = {
    a: a,
    b: "foo"
};

var bar = {
    a,
    b,
};

Example of incorrect code with the "consistent-as-needed" option, which is very similar to "consistent":

/*eslint object-shorthand: [2, "consistent-as-needed"]*/
/*eslint-env es6*/

var foo = {
    a: a,
    b: b,
};

When Not To Use It

Anyone not yet in an ES6 environment would not want to apply this rule. Others may find the terseness of the shorthand syntax harder to read and may not want to encourage it with this rule.

Further Reading

Object initializer - MDN Source: http://eslint.org/docs/rules/

  isOff:isOff,

Close

Require Object Literal Shorthand Syntax (object-shorthand)

EcmaScript 6 provides a concise form for defining object literal methods and properties. This syntax can make defining complex object literals much cleaner.

Here are a few common examples using the ES5 syntax:

// properties
var foo = {
    x: x,
    y: y,
    z: z,
};

// methods
var foo = {
    a: function() {},
    b: function() {}
};

Now here are ES6 equivalents:

/*eslint-env es6*/

// properties
var foo = {x, y, z};

// methods
var foo = {
    a() {},
    b() {}
};

Rule Details

This rule enforces the use of the shorthand syntax. This applies to all methods (including generators) defined in object literals and any properties defined where the key name matches name of the assigned variable.

Each of the following properties would warn:

/*eslint object-shorthand: "error"*/
/*eslint-env es6*/

var foo = {
    w: function() {},
    x: function *() {},
    [y]: function() {},
    z: z
};

In that case the expected syntax would have been:

/*eslint object-shorthand: "error"*/
/*eslint-env es6*/

var foo = {
    w() {},
    *x() {},
    [y]() {},
    z
};

This rule does not flag arrow functions inside of object literals. The following will not warn:

/*eslint object-shorthand: "error"*/
/*eslint-env es6*/

var foo = {
    x: (y) => y
};

Options

The rule takes an option which specifies when it should be applied. It can be set to one of the following values:

• "always" (default) expects that the shorthand will be used whenever possible.
• "methods" ensures the method shorthand is used (also applies to generators).
• "properties" ensures the property shorthand is used (where the key and variable name match).
• "never" ensures that no property or method shorthand is used in any object literal.
• "consistent" ensures that either all shorthand or all longform will be used in an object literal.
• "consistent-as-needed" ensures that either all shorthand or all longform will be used in an object literal, but ensures all shorthand whenever possible.

You can set the option in configuration like this:

{
    "object-shorthand": ["error", "always"]
}

Additionally, the rule takes an optional object configuration:

• "avoidQuotes": true indicates that longform syntax is preferred whenever the object key is a string literal (default: false). Note that this option can only be enabled when the string option is set to "always", "methods", or "properties".
• "ignoreConstructors": true can be used to prevent the rule from reporting errors for constructor functions. (By default, the rule treats constructors the same way as other functions.) Note that this option can only be enabled when the string option is set to "always" or "methods".
• "avoidExplicitReturnArrows": true indicates that methods are preferred over explicit-return arrow functions for function properties. (By default, the rule allows either of these.) Note that this option can only be enabled when the string option is set to "always" or "methods".

avoidQuotes

{
    "object-shorthand": ["error", "always", { "avoidQuotes": true }]
}

Example of incorrect code for this rule with the "always", { "avoidQuotes": true } option:

/*eslint object-shorthand: ["error", "always", { "avoidQuotes": true }]*/
/*eslint-env es6*/

var foo = {
    "bar-baz"() {}
};

Example of correct code for this rule with the "always", { "avoidQuotes": true } option:

/*eslint object-shorthand: ["error", "always", { "avoidQuotes": true }]*/
/*eslint-env es6*/

var foo = {
    "bar-baz": function() {},
    "qux": qux
};

ignoreConstructors

{
    "object-shorthand": ["error", "always", { "ignoreConstructors": true }]
}

Example of correct code for this rule with the "always", { "ignoreConstructors": true } option:

/*eslint object-shorthand: ["error", "always", { "ignoreConstructors": true }]*/
/*eslint-env es6*/

var foo = {
    ConstructorFunction: function() {}
};

avoidExplicitReturnArrows

{
    "object-shorthand": ["error", "always", { "avoidExplicitReturnArrows": true }]
}

Example of incorrect code for this rule with the "always", { "avoidExplicitReturnArrows": true } option:

/*eslint object-shorthand: ["error", "always", { "avoidExplicitReturnArrows": true }]*/
/*eslint-env es6*/

var foo = {
  foo: (bar, baz) => {
    return bar + baz;
  },

  qux: (foobar) => {
    return foobar * 2;
  }
};

Example of correct code for this rule with the "always", { "avoidExplicitReturnArrows": true } option:

/*eslint object-shorthand: ["error", "always", { "avoidExplicitReturnArrows": true }]*/
/*eslint-env es6*/

var foo = {
  foo(bar, baz) {
    return bar + baz;
  },

  qux: foobar => foobar * 2
};

Example of incorrect code for this rule with the "consistent" option:

/*eslint object-shorthand: [2, "consistent"]*/
/*eslint-env es6*/

var foo = {
    a,
    b: "foo",
};

Examples of correct code for this rule with the "consistent" option:

/*eslint object-shorthand: [2, "consistent"]*/
/*eslint-env es6*/

var foo = {
    a: a,
    b: "foo"
};

var bar = {
    a,
    b,
};

Example of incorrect code with the "consistent-as-needed" option, which is very similar to "consistent":

/*eslint object-shorthand: [2, "consistent-as-needed"]*/
/*eslint-env es6*/

var foo = {
    a: a,
    b: b,
};

When Not To Use It

Anyone not yet in an ES6 environment would not want to apply this rule. Others may find the terseness of the shorthand syntax harder to read and may not want to encourage it with this rule.

Further Reading

Object initializer - MDN Source: http://eslint.org/docs/rules/

  isOn:isOn

Close

enforce consistent spacing between keys and values in object literal properties (key-spacing)

This rule enforces spacing around the colon in object literal properties. It can verify each property individually, or it can ensure horizontal alignment of adjacent properties in an object literal.

Rule Details

This rule enforces consistent spacing between keys and values in object literal properties. In the case of long lines, it is acceptable to add a new line wherever whitespace is allowed.

Options

This rule has an object option:

• "beforeColon": false (default) disallows spaces between the key and the colon in object literals.
• "beforeColon": true requires at least one space between the key and the colon in object literals.
• "afterColon": true (default) requires at least one space between the colon and the value in object literals.
• "afterColon": false disallows spaces between the colon and the value in object literals.
• "mode": "strict" (default) enforces exactly one space before or after colons in object literals.
• "mode": "minimum" enforces one or more spaces before or after colons in object literals.
• "align": "value" enforces horizontal alignment of values in object literals.
• "align": "colon" enforces horizontal alignment of both colons and values in object literals.
• "align" with an object value allows for fine-grained spacing when values are being aligned in object literals.
• "singleLine" specifies a spacing style for single-line object literals.
• "multiLine" specifies a spacing style for multi-line object literals.

Please note that you can either use the top-level options or the grouped options (singleLine and multiLine) but not both.

beforeColon

Examples of incorrect code for this rule with the default { "beforeColon": false } option:

/*eslint key-spacing: ["error", { "beforeColon": false }]*/

var obj = { "foo" : 42 };

Examples of correct code for this rule with the default { "beforeColon": false } option:

/*eslint key-spacing: ["error", { "beforeColon": false }]*/

var obj = { "foo": 42 };

Examples of incorrect code for this rule with the { "beforeColon": true } option:

/*eslint key-spacing: ["error", { "beforeColon": true }]*/

var obj = { "foo": 42 };

Examples of correct code for this rule with the { "beforeColon": true } option:

/*eslint key-spacing: ["error", { "beforeColon": true }]*/

var obj = { "foo" : 42 };

afterColon

Examples of incorrect code for this rule with the default { "afterColon": true } option:

/*eslint key-spacing: ["error", { "afterColon": true }]*/

var obj = { "foo":42 };

Examples of correct code for this rule with the default { "afterColon": true } option:

/*eslint key-spacing: ["error", { "afterColon": true }]*/

var obj = { "foo": 42 };

Examples of incorrect code for this rule with the { "afterColon": false } option:

/*eslint key-spacing: ["error", { "afterColon": false }]*/

var obj = { "foo": 42 };

Examples of correct code for this rule with the { "afterColon": false } option:

/*eslint key-spacing: ["error", { "afterColon": false }]*/

var obj = { "foo":42 };

mode

Examples of incorrect code for this rule with the default { "mode": "strict" } option:

/*eslint key-spacing: ["error", { "mode": "strict" }]*/

call({
    foobar: 42,
    bat:    2 * 2
});

Examples of correct code for this rule with the default { "mode": "strict" } option:

/*eslint key-spacing: ["error", { "mode": "strict" }]*/

call({
    foobar: 42,
    bat: 2 * 2
});

Examples of correct code for this rule with the { "mode": "minimum" } option:

/*eslint key-spacing: ["error", { "mode": "minimum" }]*/

call({
    foobar: 42,
    bat:    2 * 2
});

align

Examples of incorrect code for this rule with the { "align": "value" } option:

/*eslint key-spacing: ["error", { "align": "value" }]*/

var obj = {
    a: value,
    bcde:  42,
    fg :   foo()
};

Examples of correct code for this rule with the { "align": "value" } option:

/*eslint key-spacing: ["error", { "align": "value" }]*/

var obj = {
    a:    value,
    bcde: 42,

    fg: foo(),
    h:  function() {
        return this.a;
    },
    ijkl: 'Non-consecutive lines form a new group'
};

var obj = { a: "foo", longPropertyName: "bar" };

Examples of incorrect code for this rule with the { "align": "colon" } option:

/*eslint key-spacing: ["error", { "align": "colon" }]*/

call({
    foobar: 42,
    bat:    2 * 2
});

Examples of correct code for this rule with the { "align": "colon" } option:

/*eslint key-spacing: ["error", { "align": "colon" }]*/

call({
    foobar: 42,
    bat   : 2 * 2
});

align

The align option can take additional configuration through the beforeColon, afterColon, mode, and on options.

If align is defined as an object, but not all of the parameters are provided, undefined parameters will default to the following:

// Defaults
align: {
    "beforeColon": false,
    "afterColon": true,
    "on": "colon",
    "mode": "strict"
}

Examples of correct code for this rule with sample { "align": { } } options:

/*eslint key-spacing: ["error", {
    "align": {
        "beforeColon": true,
        "afterColon": true,
        "on": "colon"
    }
}]*/

var obj = {
    "one"   : 1,
    "seven" : 7
}

/*eslint key-spacing: ["error", {
    "align": {
        "beforeColon": false,
        "afterColon": false,
        "on": "value"
    }
}]*/

var obj = {
    "one":  1,
    "seven":7
}

align and multiLine

The multiLine and align options can differ, which allows for fine-tuned control over the key-spacing of your files. align will not inherit from multiLine if align is configured as an object.

multiLine is used any time an object literal spans multiple lines. The align configuration is used when there is a group of properties in the same object. For example:

var myObj = {
  key1: 1, // uses multiLine

  key2: 2, // uses align (when defined)
  key3: 3, // uses align (when defined)

  key4: 4 // uses multiLine
}

Examples of incorrect code for this rule with sample { "align": { }, "multiLine": { } } options:

/*eslint key-spacing: ["error", {
    "multiLine": {
        "beforeColon": false,
        "afterColon":true
    },
    "align": {
        "beforeColon": true,
        "afterColon": true,
        "on": "colon"
    }
}]*/

var obj = {
    "myObjectFunction": function() {
        // Do something
    },
    "one"             : 1,
    "seven"           : 7
}

Examples of correct code for this rule with sample { "align": { }, "multiLine": { } } options:

/*eslint key-spacing: ["error", {
    "multiLine": {
        "beforeColon": false,
        "afterColon": true

    },
    "align": {
        "beforeColon": true,
        "afterColon": true,
        "on": "colon"
    }
}]*/

var obj = {
    "myObjectFunction": function() {
        // Do something
        //
    }, // These are two separate groups, so no alignment between `myObjectFuction` and `one`
    "one"   : 1,
    "seven" : 7 // `one` and `seven` are in their own group, and therefore aligned
}

singleLine and multiLine

Examples of correct code for this rule with sample { "singleLine": { }, "multiLine": { } } options:

/*eslint "key-spacing": [2, {
    "singleLine": {
        "beforeColon": false,
        "afterColon": true
    },
    "multiLine": {
        "beforeColon": true,
        "afterColon": true,
        "align": "colon"
    }
}]*/
var obj = { one: 1, "two": 2, three: 3 };
var obj2 = {
    "two" : 2,
    three : 3
};

When Not To Use It

If you have another convention for property spacing that might not be consistent with the available options, or if you want to permit multiple styles concurrently you can safely disable this rule. Source: http://eslint.org/docs/rules/

  load:load

Close

enforce consistent spacing between keys and values in object literal properties (key-spacing)

This rule enforces spacing around the colon in object literal properties. It can verify each property individually, or it can ensure horizontal alignment of adjacent properties in an object literal.

Rule Details

This rule enforces consistent spacing between keys and values in object literal properties. In the case of long lines, it is acceptable to add a new line wherever whitespace is allowed.

Options

This rule has an object option:

• "beforeColon": false (default) disallows spaces between the key and the colon in object literals.
• "beforeColon": true requires at least one space between the key and the colon in object literals.
• "afterColon": true (default) requires at least one space between the colon and the value in object literals.
• "afterColon": false disallows spaces between the colon and the value in object literals.
• "mode": "strict" (default) enforces exactly one space before or after colons in object literals.
• "mode": "minimum" enforces one or more spaces before or after colons in object literals.
• "align": "value" enforces horizontal alignment of values in object literals.
• "align": "colon" enforces horizontal alignment of both colons and values in object literals.
• "align" with an object value allows for fine-grained spacing when values are being aligned in object literals.
• "singleLine" specifies a spacing style for single-line object literals.
• "multiLine" specifies a spacing style for multi-line object literals.

Please note that you can either use the top-level options or the grouped options (singleLine and multiLine) but not both.

beforeColon

Examples of incorrect code for this rule with the default { "beforeColon": false } option:

/*eslint key-spacing: ["error", { "beforeColon": false }]*/

var obj = { "foo" : 42 };

Examples of correct code for this rule with the default { "beforeColon": false } option:

/*eslint key-spacing: ["error", { "beforeColon": false }]*/

var obj = { "foo": 42 };

Examples of incorrect code for this rule with the { "beforeColon": true } option:

/*eslint key-spacing: ["error", { "beforeColon": true }]*/

var obj = { "foo": 42 };

Examples of correct code for this rule with the { "beforeColon": true } option:

/*eslint key-spacing: ["error", { "beforeColon": true }]*/

var obj = { "foo" : 42 };

afterColon

Examples of incorrect code for this rule with the default { "afterColon": true } option:

/*eslint key-spacing: ["error", { "afterColon": true }]*/

var obj = { "foo":42 };

Examples of correct code for this rule with the default { "afterColon": true } option:

/*eslint key-spacing: ["error", { "afterColon": true }]*/

var obj = { "foo": 42 };

Examples of incorrect code for this rule with the { "afterColon": false } option:

/*eslint key-spacing: ["error", { "afterColon": false }]*/

var obj = { "foo": 42 };

Examples of correct code for this rule with the { "afterColon": false } option:

/*eslint key-spacing: ["error", { "afterColon": false }]*/

var obj = { "foo":42 };

mode

Examples of incorrect code for this rule with the default { "mode": "strict" } option:

/*eslint key-spacing: ["error", { "mode": "strict" }]*/

call({
    foobar: 42,
    bat:    2 * 2
});

Examples of correct code for this rule with the default { "mode": "strict" } option:

/*eslint key-spacing: ["error", { "mode": "strict" }]*/

call({
    foobar: 42,
    bat: 2 * 2
});

Examples of correct code for this rule with the { "mode": "minimum" } option:

/*eslint key-spacing: ["error", { "mode": "minimum" }]*/

call({
    foobar: 42,
    bat:    2 * 2
});

align

Examples of incorrect code for this rule with the { "align": "value" } option:

/*eslint key-spacing: ["error", { "align": "value" }]*/

var obj = {
    a: value,
    bcde:  42,
    fg :   foo()
};

Examples of correct code for this rule with the { "align": "value" } option:

/*eslint key-spacing: ["error", { "align": "value" }]*/

var obj = {
    a:    value,
    bcde: 42,

    fg: foo(),
    h:  function() {
        return this.a;
    },
    ijkl: 'Non-consecutive lines form a new group'
};

var obj = { a: "foo", longPropertyName: "bar" };

Examples of incorrect code for this rule with the { "align": "colon" } option:

/*eslint key-spacing: ["error", { "align": "colon" }]*/

call({
    foobar: 42,
    bat:    2 * 2
});

Examples of correct code for this rule with the { "align": "colon" } option:

/*eslint key-spacing: ["error", { "align": "colon" }]*/

call({
    foobar: 42,
    bat   : 2 * 2
});

align

The align option can take additional configuration through the beforeColon, afterColon, mode, and on options.

If align is defined as an object, but not all of the parameters are provided, undefined parameters will default to the following:

// Defaults
align: {
    "beforeColon": false,
    "afterColon": true,
    "on": "colon",
    "mode": "strict"
}

Examples of correct code for this rule with sample { "align": { } } options:

/*eslint key-spacing: ["error", {
    "align": {
        "beforeColon": true,
        "afterColon": true,
        "on": "colon"
    }
}]*/

var obj = {
    "one"   : 1,
    "seven" : 7
}

/*eslint key-spacing: ["error", {
    "align": {
        "beforeColon": false,
        "afterColon": false,
        "on": "value"
    }
}]*/

var obj = {
    "one":  1,
    "seven":7
}

align and multiLine

The multiLine and align options can differ, which allows for fine-tuned control over the key-spacing of your files. align will not inherit from multiLine if align is configured as an object.

multiLine is used any time an object literal spans multiple lines. The align configuration is used when there is a group of properties in the same object. For example:

var myObj = {
  key1: 1, // uses multiLine

  key2: 2, // uses align (when defined)
  key3: 3, // uses align (when defined)

  key4: 4 // uses multiLine
}

Examples of incorrect code for this rule with sample { "align": { }, "multiLine": { } } options:

/*eslint key-spacing: ["error", {
    "multiLine": {
        "beforeColon": false,
        "afterColon":true
    },
    "align": {
        "beforeColon": true,
        "afterColon": true,
        "on": "colon"
    }
}]*/

var obj = {
    "myObjectFunction": function() {
        // Do something
    },
    "one"             : 1,
    "seven"           : 7
}

Examples of correct code for this rule with sample { "align": { }, "multiLine": { } } options:

/*eslint key-spacing: ["error", {
    "multiLine": {
        "beforeColon": false,
        "afterColon": true

    },
    "align": {
        "beforeColon": true,
        "afterColon": true,
        "on": "colon"
    }
}]*/

var obj = {
    "myObjectFunction": function() {
        // Do something
        //
    }, // These are two separate groups, so no alignment between `myObjectFuction` and `one`
    "one"   : 1,
    "seven" : 7 // `one` and `seven` are in their own group, and therefore aligned
}

singleLine and multiLine

Examples of correct code for this rule with sample { "singleLine": { }, "multiLine": { } } options:

/*eslint "key-spacing": [2, {
    "singleLine": {
        "beforeColon": false,
        "afterColon": true
    },
    "multiLine": {
        "beforeColon": true,
        "afterColon": true,
        "align": "colon"
    }
}]*/
var obj = { one: 1, "two": 2, three: 3 };
var obj2 = {
    "two" : 2,
    three : 3
};

When Not To Use It

If you have another convention for property spacing that might not be consistent with the available options, or if you want to permit multiple styles concurrently you can safely disable this rule. Source: http://eslint.org/docs/rules/

function _setAllIcons() {

Close

disallow dangling underscores in identifiers (no-underscore-dangle)

As far as naming conventions for identifiers go, dangling underscores may be the most polarizing in JavaScript. Dangling underscores are underscores at either the beginning or end of an identifier, such as:

var _foo;

There is actually a long history of using dangling underscores to indicate "private" members of objects in JavaScript (though JavaScript doesn't have truly private members, this convention served as a warning). This began with SpiderMonkey adding nonstandard methods such as __defineGetter__(). The intent with the underscores was to make it obvious that this method was special in some way. Since that time, using a single underscore prefix has become popular as a way to indicate "private" members of objects.

Whether or not you choose to allow dangling underscores in identifiers is purely a convention and has no effect on performance, readability, or complexity. It's purely a preference.

Rule Details

This rule disallows dangling underscores in identifiers.

Examples of incorrect code for this rule:

/*eslint no-underscore-dangle: "error"*/

var foo_;
var __proto__ = {};
foo._bar();

Examples of correct code for this rule:

/*eslint no-underscore-dangle: "error"*/

var _ = require('underscore');
var obj = _.contains(items, item);
obj.__proto__ = {};
var file = __filename;

Options

This rule has an object option:

• "allow" allows specified identifiers to have dangling underscores
• "allowAfterThis": false (default) disallows dangling underscores in members of the this object
• "allowAfterSuper": false (default) disallows dangling underscores in members of the super object

allow

Examples of additional correct code for this rule with the { "allow": ["foo_", "_bar"] } option:

/*eslint no-underscore-dangle: ["error", { "allow": ["foo_", "_bar"] }]*/

var foo_;
foo._bar();

allowAfterThis

Examples of correct code for this rule with the { "allowAfterThis": true } option:

/*eslint no-underscore-dangle: ["error", { "allowAfterThis": true }]*/

var a = this.foo_;
this._bar();

allowAfterSuper

Examples of correct code for this rule with the { "allowAfterSuper": true } option:

/*eslint no-underscore-dangle: ["error", { "allowAfterSuper": true }]*/

var a = super.foo_;
super._bar();

When Not To Use It

If you want to allow dangling underscores in identifiers, then you can safely turn this rule off. Source: http://eslint.org/docs/rules/

    _setIcon(markers[index--], false);

Close

Disallow Early Use (no-use-before-define)

In JavaScript, prior to ES6, variable and function declarations are hoisted to the top of a scope, so it's possible to use identifiers before their formal declarations in code. This can be confusing and some believe it is best to always declare variables and functions before using them.

In ES6, block-level bindings (let and const) introduce a "temporal dead zone" where a ReferenceError will be thrown with any attempt to access the variable before its declaration.

Rule Details

This rule will warn when it encounters a reference to an identifier that has not yet been declared.

Examples of incorrect code for this rule:

/*eslint no-use-before-define: "error"*/
/*eslint-env es6*/

alert(a);
var a = 10;

f();
function f() {}

function g() {
    return b;
}
var b = 1;

// With blockBindings: true
{
    alert(c);
    let c = 1;
}

Examples of correct code for this rule:

/*eslint no-use-before-define: "error"*/
/*eslint-env es6*/

var a;
a = 10;
alert(a);

function f() {}
f(1);

var b = 1;
function g() {
    return b;
}

// With blockBindings: true
{
    let C;
    c++;
}

Options

{
    "no-use-before-define": ["error", { "functions": true, "classes": true }]
}

• functions (boolean) - The flag which shows whether or not this rule checks function declarations. If this is true, this rule warns every reference to a function before the function declaration. Otherwise, ignores those references. Function declarations are hoisted, so it's safe. Default is true.
• classes (boolean) - The flag which shows whether or not this rule checks class declarations of upper scopes. If this is true, this rule warns every reference to a class before the class declaration. Otherwise, ignores those references if the declaration is in upper function scopes. Class declarations are not hoisted, so it might be danger. Default is true.
• variables (boolean) - This flag determines whether or not the rule checks variable declarations in upper scopes. If this is true, the rule warns every reference to a variable before the variable declaration. Otherwise, the rule ignores a reference if the declaration is in an upper scope, while still reporting the reference if it's in the same scope as the declaration. Default is true.

This rule accepts "nofunc" string as an option. "nofunc" is the same as { "functions": false, "classes": true }.

functions

Examples of correct code for the { "functions": false } option:

/*eslint no-use-before-define: ["error", { "functions": false }]*/

f();
function f() {}

classes

Examples of incorrect code for the { "classes": false } option:

/*eslint no-use-before-define: ["error", { "classes": false }]*/
/*eslint-env es6*/

new A();
class A {
}

Examples of correct code for the { "classes": false } option:

/*eslint no-use-before-define: ["error", { "classes": false }]*/
/*eslint-env es6*/

function foo() {
    return new A();
}

class A {
}

variables

Examples of incorrect code for the { "variables": false } option:

/*eslint no-use-before-define: ["error", { "variables": false }]*/

console.log(foo);
var foo = 1;

Examples of correct code for the { "variables": false } option:

/*eslint no-use-before-define: ["error", { "variables": false }]*/

function baz() {
    console.log(foo);
}

var foo = 1;

Source: http://eslint.org/docs/rules/

  var manager = marker.manager;

Close

require let or const instead of var (no-var)

ECMAScript 6 allows programmers to create variables with block scope instead of function scope using the let and const keywords. Block scope is common in many other programming languages and helps programmers avoid mistakes such as:

var count = people.length;
var enoughFood = count > sandwiches.length;

if (enoughFood) {
    var count = sandwiches.length; // accidentally overriding the count variable
    console.log("We have " + count + " sandwiches for everyone. Plenty for all!");
}

// our count variable is no longer accurate
console.log("We have " + count + " people and " + sandwiches.length + " sandwiches!");

Rule Details

This rule is aimed at discouraging the use of var and encouraging the use of const or let instead.

Examples

Examples of incorrect code for this rule:

/*eslint no-var: "error"*/

var x = "y";
var CONFIG = {};

Examples of correct code for this rule:

/*eslint no-var: "error"*/
/*eslint-env es6*/

let x = "y";
const CONFIG = {};

When Not To Use It

In addition to non-ES6 environments, existing JavaScript projects that are beginning to introduce ES6 into their codebase may not want to apply this rule if the cost of migrating from var to let is too costly. Source: http://eslint.org/docs/rules/

    var index = spiderfied.length - 1;

Close

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 for case clauses in switch statements
• "VariableDeclarator" (default: 1) enforces indentation level for var declarators; can also take an object to define separate rules for var, let and const 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 to 2 will indent the multi-line variable declarations with 8 spaces.
• Indent of 2 spaces with VariableDeclarator set to 2 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 for var and let, 6 spaces for const statements.
• Indent of tab with VariableDeclarator set to 2 will indent the multi-line variable declarations with 2 tabs.
• Indent of 2 spaces with SwitchCase set to 0 will not indent case clauses with respect to switch statements.
• Indent of 2 spaces with SwitchCase set to 1 will indent case clauses with 2 spaces with respect to switch statements.
• Indent of 2 spaces with SwitchCase set to 2 will indent case clauses with 4 spaces with respect to switch statements.
• Indent of tab with SwitchCase set to 2 will indent case clauses with 2 tabs with respect to switch statements.
• Indent of 2 spaces with MemberExpression set to 0 will indent the multi-line property chains with 0 spaces.
• Indent of 2 spaces with MemberExpression set to 1 will indent the multi-line property chains with 2 spaces.
• Indent of 2 spaces with MemberExpression set to 2 will indent the multi-line property chains with 4 spaces.
• Indent of 4 spaces with MemberExpression set to 0 will indent the multi-line property chains with 0 spaces.
• Indent of 4 spaces with MemberExpression set to 1 will indent the multi-line property chains with 4 spaces.
• Indent of 4 spaces with MemberExpression set to 2 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/

    var poiStyles =[

Close

require let or const instead of var (no-var)

ECMAScript 6 allows programmers to create variables with block scope instead of function scope using the let and const keywords. Block scope is common in many other programming languages and helps programmers avoid mistakes such as:

var count = people.length;
var enoughFood = count > sandwiches.length;

if (enoughFood) {
    var count = sandwiches.length; // accidentally overriding the count variable
    console.log("We have " + count + " sandwiches for everyone. Plenty for all!");
}

// our count variable is no longer accurate
console.log("We have " + count + " people and " + sandwiches.length + " sandwiches!");

Rule Details

This rule is aimed at discouraging the use of var and encouraging the use of const or let instead.

Examples

Examples of incorrect code for this rule:

/*eslint no-var: "error"*/

var x = "y";
var CONFIG = {};

Examples of correct code for this rule:

/*eslint no-var: "error"*/
/*eslint-env es6*/

let x = "y";
const CONFIG = {};

When Not To Use It

In addition to non-ES6 environments, existing JavaScript projects that are beginning to introduce ES6 into their codebase may not want to apply this rule if the cost of migrating from var to let is too costly. Source: http://eslint.org/docs/rules/

    var poiStyles =[

Close

require spacing around infix operators (space-infix-ops)

While formatting preferences are very personal, a number of style guides require spaces around operators, such as:

var sum = 1 + 2;

The proponents of these extra spaces believe it make the code easier to read and can more easily highlight potential errors, such as:

var sum = i+++2;

While this is valid JavaScript syntax, it is hard to determine what the author intended.

Rule Details

This rule is aimed at ensuring there are spaces around infix operators.

Options

This rule accepts a single options argument with the following defaults:

"space-infix-ops": ["error", {"int32Hint": false}]

int32Hint

Set the int32Hint option to true (default is false) to allow write a|0 without space.

var foo = bar|0; // `foo` is forced to be signed 32 bit integer

Examples of incorrect code for this rule:

/*eslint space-infix-ops: "error"*/
/*eslint-env es6*/

a+b

a+ b

a +b

a?b:c

const a={b:1};

var {a=0}=bar;

function foo(a=0) { }

Examples of correct code for this rule:

/*eslint space-infix-ops: "error"*/
/*eslint-env es6*/

a + b

a       + b

a ? b : c

const a = {b:1};

var {a = 0} = bar;

function foo(a = 0) { }

Source: http://eslint.org/docs/rules/

  loadData:loadData,

Close

enforce consistent spacing between keys and values in object literal properties (key-spacing)

This rule enforces spacing around the colon in object literal properties. It can verify each property individually, or it can ensure horizontal alignment of adjacent properties in an object literal.

Rule Details

This rule enforces consistent spacing between keys and values in object literal properties. In the case of long lines, it is acceptable to add a new line wherever whitespace is allowed.

Options

This rule has an object option:

• "beforeColon": false (default) disallows spaces between the key and the colon in object literals.
• "beforeColon": true requires at least one space between the key and the colon in object literals.
• "afterColon": true (default) requires at least one space between the colon and the value in object literals.
• "afterColon": false disallows spaces between the colon and the value in object literals.
• "mode": "strict" (default) enforces exactly one space before or after colons in object literals.
• "mode": "minimum" enforces one or more spaces before or after colons in object literals.
• "align": "value" enforces horizontal alignment of values in object literals.
• "align": "colon" enforces horizontal alignment of both colons and values in object literals.
• "align" with an object value allows for fine-grained spacing when values are being aligned in object literals.
• "singleLine" specifies a spacing style for single-line object literals.
• "multiLine" specifies a spacing style for multi-line object literals.

Please note that you can either use the top-level options or the grouped options (singleLine and multiLine) but not both.

beforeColon

Examples of incorrect code for this rule with the default { "beforeColon": false } option:

/*eslint key-spacing: ["error", { "beforeColon": false }]*/

var obj = { "foo" : 42 };

Examples of correct code for this rule with the default { "beforeColon": false } option:

/*eslint key-spacing: ["error", { "beforeColon": false }]*/

var obj = { "foo": 42 };

Examples of incorrect code for this rule with the { "beforeColon": true } option:

/*eslint key-spacing: ["error", { "beforeColon": true }]*/

var obj = { "foo": 42 };

Examples of correct code for this rule with the { "beforeColon": true } option:

/*eslint key-spacing: ["error", { "beforeColon": true }]*/

var obj = { "foo" : 42 };

afterColon

Examples of incorrect code for this rule with the default { "afterColon": true } option:

/*eslint key-spacing: ["error", { "afterColon": true }]*/

var obj = { "foo":42 };

Examples of correct code for this rule with the default { "afterColon": true } option:

/*eslint key-spacing: ["error", { "afterColon": true }]*/

var obj = { "foo": 42 };

Examples of incorrect code for this rule with the { "afterColon": false } option:

/*eslint key-spacing: ["error", { "afterColon": false }]*/

var obj = { "foo": 42 };

Examples of correct code for this rule with the { "afterColon": false } option:

/*eslint key-spacing: ["error", { "afterColon": false }]*/

var obj = { "foo":42 };

mode

Examples of incorrect code for this rule with the default { "mode": "strict" } option:

/*eslint key-spacing: ["error", { "mode": "strict" }]*/

call({
    foobar: 42,
    bat:    2 * 2
});

Examples of correct code for this rule with the default { "mode": "strict" } option:

/*eslint key-spacing: ["error", { "mode": "strict" }]*/

call({
    foobar: 42,
    bat: 2 * 2
});

Examples of correct code for this rule with the { "mode": "minimum" } option:

/*eslint key-spacing: ["error", { "mode": "minimum" }]*/

call({
    foobar: 42,
    bat:    2 * 2
});

align

Examples of incorrect code for this rule with the { "align": "value" } option:

/*eslint key-spacing: ["error", { "align": "value" }]*/

var obj = {
    a: value,
    bcde:  42,
    fg :   foo()
};

Examples of correct code for this rule with the { "align": "value" } option:

/*eslint key-spacing: ["error", { "align": "value" }]*/

var obj = {
    a:    value,
    bcde: 42,

    fg: foo(),
    h:  function() {
        return this.a;
    },
    ijkl: 'Non-consecutive lines form a new group'
};

var obj = { a: "foo", longPropertyName: "bar" };

Examples of incorrect code for this rule with the { "align": "colon" } option:

/*eslint key-spacing: ["error", { "align": "colon" }]*/

call({
    foobar: 42,
    bat:    2 * 2
});

Examples of correct code for this rule with the { "align": "colon" } option:

/*eslint key-spacing: ["error", { "align": "colon" }]*/

call({
    foobar: 42,
    bat   : 2 * 2
});

align

The align option can take additional configuration through the beforeColon, afterColon, mode, and on options.

If align is defined as an object, but not all of the parameters are provided, undefined parameters will default to the following:

// Defaults
align: {
    "beforeColon": false,
    "afterColon": true,
    "on": "colon",
    "mode": "strict"
}

Examples of correct code for this rule with sample { "align": { } } options:

/*eslint key-spacing: ["error", {
    "align": {
        "beforeColon": true,
        "afterColon": true,
        "on": "colon"
    }
}]*/

var obj = {
    "one"   : 1,
    "seven" : 7
}

/*eslint key-spacing: ["error", {
    "align": {
        "beforeColon": false,
        "afterColon": false,
        "on": "value"
    }
}]*/

var obj = {
    "one":  1,
    "seven":7
}

align and multiLine

The multiLine and align options can differ, which allows for fine-tuned control over the key-spacing of your files. align will not inherit from multiLine if align is configured as an object.

multiLine is used any time an object literal spans multiple lines. The align configuration is used when there is a group of properties in the same object. For example:

var myObj = {
  key1: 1, // uses multiLine

  key2: 2, // uses align (when defined)
  key3: 3, // uses align (when defined)

  key4: 4 // uses multiLine
}

Examples of incorrect code for this rule with sample { "align": { }, "multiLine": { } } options:

/*eslint key-spacing: ["error", {
    "multiLine": {
        "beforeColon": false,
        "afterColon":true
    },
    "align": {
        "beforeColon": true,
        "afterColon": true,
        "on": "colon"
    }
}]*/

var obj = {
    "myObjectFunction": function() {
        // Do something
    },
    "one"             : 1,
    "seven"           : 7
}

Examples of correct code for this rule with sample { "align": { }, "multiLine": { } } options:

/*eslint key-spacing: ["error", {
    "multiLine": {
        "beforeColon": false,
        "afterColon": true

    },
    "align": {
        "beforeColon": true,
        "afterColon": true,
        "on": "colon"
    }
}]*/

var obj = {
    "myObjectFunction": function() {
        // Do something
        //
    }, // These are two separate groups, so no alignment between `myObjectFuction` and `one`
    "one"   : 1,
    "seven" : 7 // `one` and `seven` are in their own group, and therefore aligned
}

singleLine and multiLine

Examples of correct code for this rule with sample { "singleLine": { }, "multiLine": { } } options:

/*eslint "key-spacing": [2, {
    "singleLine": {
        "beforeColon": false,
        "afterColon": true
    },
    "multiLine": {
        "beforeColon": true,
        "afterColon": true,
        "align": "colon"
    }
}]*/
var obj = { one: 1, "two": 2, three: 3 };
var obj2 = {
    "two" : 2,
    three : 3
};

When Not To Use It

If you have another convention for property spacing that might not be consistent with the available options, or if you want to permit multiple styles concurrently you can safely disable this rule. Source: http://eslint.org/docs/rules/

    'submit': 'form',

Close

require quotes around object literal property names (quote-props)

Object literal property names can be defined in two ways: using literals or using strings. For example, these two objects are equivalent:

var object1 = {
    property: true
};

var object2 = {
    "property": true
};

In many cases, it doesn't matter if you choose to use an identifier instead of a string or vice-versa. Even so, you might decide to enforce a consistent style in your code.

There are, however, some occasions when you must use quotes:

1. If you are using an ECMAScript 3 JavaScript engine (such as IE8) and you want to use a keyword (such as if) as a property name. This restriction was removed in ECMAScript 5.
2. You want to use a non-identifier character in your property name, such as having a property with a space like "one two".

Another example where quotes do matter is when using numeric literals as property keys:

var object = {
    1e2: 1,
    100: 2
};

This may look alright at first sight, but this code in fact throws a syntax error in ECMAScript 5 strict mode. This happens because 1e2 and 100 are coerced into strings before getting used as the property name. Both String(1e2) and String(100) happen to be equal to "100", which causes the "Duplicate data property in object literal not allowed in strict mode" error. Issues like that can be tricky to debug, so some prefer to require quotes around all property names.

Rule Details

This rule requires quotes around object literal property names.

Options

This rule has two options, a string option and an object option.

String option:

• "always" (default) requires quotes around all object literal property names
• "as-needed" disallows quotes around object literal property names that are not strictly required
• "consistent" enforces a consistent quote style requires quotes around object literal property names
• "consistent-as-needed" requires quotes around all object literal property names if any name strictly requires quotes, otherwise disallows quotes around object property names

Object option:

• "keywords": true requires quotes around language keywords used as object property names (only applies when using as-needed or consistent-as-needed)
• "unnecessary": true (default) disallows quotes around object literal property names that are not strictly required (only applies when using as-needed)
• "unnecessary": false allows quotes around object literal property names that are not strictly required (only applies when using as-needed)
• "numbers": true requires quotes around numbers used as object property names (only applies when using as-needed)

always

Examples of incorrect code for this rule with the default "always" option:

/*eslint quote-props: ["error", "always"]*/

var object = {
    foo: "bar",
    baz: 42,
    "qux-lorem": true
};

Examples of correct code for this rule with the default "always" option:

/*eslint quote-props: ["error", "always"]*/
/*eslint-env es6*/

var object1 = {
    "foo": "bar",
    "baz": 42,
    "qux-lorem": true
};

var object2 = {
    'foo': 'bar',
    'baz': 42,
    'qux-lorem': true
};

var object3 = {
    foo() {
        return;
    }
};

as-needed

Examples of incorrect code for this rule with the "as-needed" option:

/*eslint quote-props: ["error", "as-needed"]*/

var object = {
    "a": 0,
    "0": 0,
    "true": 0,
    "null": 0
};

Examples of correct code for this rule with the "as-needed" option:

/*eslint quote-props: ["error", "as-needed"]*/
/*eslint-env es6*/

var object1 = {
    "a-b": 0,
    "0x0": 0,
    "1e2": 0
};

var object2 = {
    foo: 'bar',
    baz: 42,
    true: 0,
    0: 0,
    'qux-lorem': true
};

var object3 = {
    foo() {
        return;
    }
};

consistent

Examples of incorrect code for this rule with the "consistent" option:

/*eslint quote-props: ["error", "consistent"]*/

var object1 = {
    foo: "bar",
    "baz": 42,
    "qux-lorem": true
};

var object2 = {
    'foo': 'bar',
    baz: 42
};

Examples of correct code for this rule with the "consistent" option:

/*eslint quote-props: ["error", "consistent"]*/

var object1 = {
    "foo": "bar",
    "baz": 42,
    "qux-lorem": true
};

var object2 = {
    'foo': 'bar',
    'baz': 42
};

var object3 = {
    foo: 'bar',
    baz: 42
};

consistent-as-needed

Examples of incorrect code for this rule with the "consistent-as-needed" option:

/*eslint quote-props: ["error", "consistent-as-needed"]*/

var object1 = {
    foo: "bar",
    "baz": 42,
    "qux-lorem": true
};

var object2 = {
    'foo': 'bar',
    'baz': 42
};

Examples of correct code for this rule with the "consistent-as-needed" option:

/*eslint quote-props: ["error", "consistent-as-needed"]*/

var object1 = {
    "foo": "bar",
    "baz": 42,
    "qux-lorem": true
};

var object2 = {
    foo: 'bar',
    baz: 42
};

keywords

Examples of additional incorrect code for this rule with the "as-needed", { "keywords": true } options:

/*eslint quote-props: ["error", "as-needed", { "keywords": true }]*/

var x = {
    while: 1,
    volatile: "foo"
};

Examples of additional incorrect code for this rule with the "consistent-as-needed", { "keywords": true } options:

/*eslint quote-props: ["error", "consistent-as-needed", { "keywords": true }]*/

var x = {
    "prop": 1,
    "bar": "foo"
};

unnecessary

Examples of additional correct code for this rule with the "as-needed", { "unnecessary": false } options:

/*eslint quote-props: ["error", "as-needed", { "keywords": true, "unnecessary": false }]*/

var x = {
    "while": 1,
    "foo": "bar"  // Would normally have caused a warning
};

numbers

Examples of additional incorrect code for this rule with the "as-needed", { "numbers": true } options:

/*eslint quote-props: ["error", "as-needed", { "numbers": true }]*/

var x = {
    100: 1
}

When Not To Use It

If you don't care if property names are consistently wrapped in quotes or not, and you don't target legacy ES3 environments, turn this rule off.

Further Reading

• Reserved words as property names
• Unquoted property names / object keys in JavaScript Source: http://eslint.org/docs/rules/

  } else if ( document.documentElement &&

Close

Disallow or enforce spaces inside of parentheses (space-in-parens)

Some style guides require or disallow spaces inside of parentheses:

foo( 'bar' );
var x = ( 1 + 2 ) * 3;

foo('bar');
var x = (1 + 2) * 3;

Rule Details

This rule will enforce consistency of spacing directly inside of parentheses, by disallowing or requiring one or more spaces to the right of ( and to the left of ). In either case, () will still be allowed.

Options

There are two options for this rule:

• "never" (default) enforces zero spaces inside of parentheses
• "always" enforces a space inside of parentheses

Depending on your coding conventions, you can choose either option by specifying it in your configuration:

"space-in-parens": ["error", "always"]

"never"

Examples of incorrect code for this rule with the default "never" option:

/*eslint space-in-parens: ["error", "never"]*/

foo( 'bar');
foo('bar' );
foo( 'bar' );

var foo = ( 1 + 2 ) * 3;
( function () { return 'bar'; }() );

Examples of correct code for this rule with the default "never" option:

/*eslint space-in-parens: ["error", "never"]*/

foo();

foo('bar');

var foo = (1 + 2) * 3;
(function () { return 'bar'; }());

"always"

Examples of incorrect code for this rule with the "always" option:

/*eslint space-in-parens: ["error", "always"]*/

foo( 'bar');
foo('bar' );
foo('bar');

var foo = (1 + 2) * 3;
(function () { return 'bar'; }());

Examples of correct code for this rule with the "always" option:

/*eslint space-in-parens: ["error", "always"]*/

foo();

foo( 'bar' );

var foo = ( 1 + 2 ) * 3;
( function () { return 'bar'; }() );

Exceptions

An object literal may be used as a third array item to specify exceptions, with the key "exceptions" and an array as the value. These exceptions work in the context of the first option. That is, if "always" is set to enforce spacing, then any "exception" will disallow spacing. Conversely, if "never" is set to disallow spacing, then any "exception" will enforce spacing.

The following exceptions are available: ["{}", "[]", "()", "empty"].

Examples of incorrect code for this rule with the "never", { "exceptions": ["{}"] } option:

/*eslint space-in-parens: ["error", "never", { "exceptions": ["{}"] }]*/

foo({bar: 'baz'});
foo(1, {bar: 'baz'});

Examples of correct code for this rule with the "never", { "exceptions": ["{}"] } option:

/*eslint space-in-parens: ["error", "never", { "exceptions": ["{}"] }]*/

foo( {bar: 'baz'} );
foo(1, {bar: 'baz'} );

Examples of incorrect code for this rule with the "always", { "exceptions": ["{}"] } option:

/*eslint space-in-parens: ["error", "always", { "exceptions": ["{}"] }]*/

foo( {bar: 'baz'} );
foo( 1, {bar: 'baz'} );

Examples of correct code for this rule with the "always", { "exceptions": ["{}"] } option:

/*eslint space-in-parens: ["error", "always", { "exceptions": ["{}"] }]*/

foo({bar: 'baz'});
foo( 1, {bar: 'baz'});

Examples of incorrect code for this rule with the "never", { "exceptions": ["[]"] } option:

/*eslint space-in-parens: ["error", "never", { "exceptions": ["[]"] }]*/

foo([bar, baz]);
foo([bar, baz], 1);

Examples of correct code for this rule with the "never", { "exceptions": ["[]"] } option:

/*eslint space-in-parens: ["error", "never", { "exceptions": ["[]"] }]*/

foo( [bar, baz] );
foo( [bar, baz], 1);

Examples of incorrect code for this rule with the "always", { "exceptions": ["[]"] } option:

/*eslint space-in-parens: ["error", "always", { "exceptions": ["[]"] }]*/

foo( [bar, baz] );
foo( [bar, baz], 1 );

Examples of correct code for this rule with the "always", { "exceptions": ["[]"] } option:

/*eslint space-in-parens: ["error", "always", { "exceptions": ["[]"] }]*/

foo([bar, baz]);
foo([bar, baz], 1 );

Examples of incorrect code for this rule with the "never", { "exceptions": ["()"] }] option:

/*eslint space-in-parens: ["error", "never", { "exceptions": ["()"] }]*/

foo((1 + 2));
foo((1 + 2), 1);

Examples of correct code for this rule with the "never", { "exceptions": ["()"] }] option:

/*eslint space-in-parens: ["error", "never", { "exceptions": ["()"] }]*/

foo( (1 + 2) );
foo( (1 + 2), 1);

Examples of incorrect code for this rule with the "always", { "exceptions": ["()"] }] option:

/*eslint space-in-parens: ["error", "always", { "exceptions": ["()"] }]*/

foo( ( 1 + 2 ) );
foo( ( 1 + 2 ), 1 );

Examples of correct code for this rule with the "always", { "exceptions": ["()"] }] option:

/*eslint space-in-parens: ["error", "always", { "exceptions": ["()"] }]*/

foo(( 1 + 2 ));
foo(( 1 + 2 ), 1 );

The "empty" exception concerns empty parentheses, and works the same way as the other exceptions, inverting the first option.

Example of incorrect code for this rule with the "never", { "exceptions": ["empty"] }] option:

/*eslint space-in-parens: ["error", "never", { "exceptions": ["empty"] }]*/

foo();

Example of correct code for this rule with the "never", { "exceptions": ["empty"] }] option:

/*eslint space-in-parens: ["error", "never", { "exceptions": ["empty"] }]*/

foo( );

Example of incorrect code for this rule with the "always", { "exceptions": ["empty"] }] option:

/*eslint space-in-parens: ["error", "always", { "exceptions": ["empty"] }]*/

foo( );

Example of correct code for this rule with the "always", { "exceptions": ["empty"] }] option:

/*eslint space-in-parens: ["error", "always", { "exceptions": ["empty"] }]*/

foo();

You can include multiple entries in the "exceptions" array.

Examples of incorrect code for this rule with the "always", { "exceptions": ["{}", "[]"] }] option:

/*eslint space-in-parens: ["error", "always", { "exceptions": ["{}", "[]"] }]*/

bar( {bar:'baz'} );
baz( 1, [1,2] );
foo( {bar: 'baz'}, [1, 2] );

Examples of correct code for this rule with the "always", { "exceptions": ["{}", "[]"] }] option:

/*eslint space-in-parens: ["error", "always", { "exceptions": ["{}", "[]"] }]*/

bar({bar:'baz'});
baz( 1, [1,2]);
foo({bar: 'baz'}, [1, 2]);

When Not To Use It

You can turn this rule off if you are not concerned with the consistency of spacing between parentheses.

Related Rules

• [space-in-brackets](space-in-brackets.md) (deprecated) Source: http://eslint.org/docs/rules/

    'height':myHeight

Close

enforce consistent spacing between keys and values in object literal properties (key-spacing)

This rule enforces spacing around the colon in object literal properties. It can verify each property individually, or it can ensure horizontal alignment of adjacent properties in an object literal.

Rule Details

This rule enforces consistent spacing between keys and values in object literal properties. In the case of long lines, it is acceptable to add a new line wherever whitespace is allowed.

Options

This rule has an object option:

• "beforeColon": false (default) disallows spaces between the key and the colon in object literals.
• "beforeColon": true requires at least one space between the key and the colon in object literals.
• "afterColon": true (default) requires at least one space between the colon and the value in object literals.
• "afterColon": false disallows spaces between the colon and the value in object literals.
• "mode": "strict" (default) enforces exactly one space before or after colons in object literals.
• "mode": "minimum" enforces one or more spaces before or after colons in object literals.
• "align": "value" enforces horizontal alignment of values in object literals.
• "align": "colon" enforces horizontal alignment of both colons and values in object literals.
• "align" with an object value allows for fine-grained spacing when values are being aligned in object literals.
• "singleLine" specifies a spacing style for single-line object literals.
• "multiLine" specifies a spacing style for multi-line object literals.

Please note that you can either use the top-level options or the grouped options (singleLine and multiLine) but not both.

beforeColon

Examples of incorrect code for this rule with the default { "beforeColon": false } option:

/*eslint key-spacing: ["error", { "beforeColon": false }]*/

var obj = { "foo" : 42 };

Examples of correct code for this rule with the default { "beforeColon": false } option:

/*eslint key-spacing: ["error", { "beforeColon": false }]*/

var obj = { "foo": 42 };

Examples of incorrect code for this rule with the { "beforeColon": true } option:

/*eslint key-spacing: ["error", { "beforeColon": true }]*/

var obj = { "foo": 42 };

Examples of correct code for this rule with the { "beforeColon": true } option:

/*eslint key-spacing: ["error", { "beforeColon": true }]*/

var obj = { "foo" : 42 };

afterColon

Examples of incorrect code for this rule with the default { "afterColon": true } option:

/*eslint key-spacing: ["error", { "afterColon": true }]*/

var obj = { "foo":42 };

Examples of correct code for this rule with the default { "afterColon": true } option:

/*eslint key-spacing: ["error", { "afterColon": true }]*/

var obj = { "foo": 42 };

Examples of incorrect code for this rule with the { "afterColon": false } option:

/*eslint key-spacing: ["error", { "afterColon": false }]*/

var obj = { "foo": 42 };

Examples of correct code for this rule with the { "afterColon": false } option:

/*eslint key-spacing: ["error", { "afterColon": false }]*/

var obj = { "foo":42 };

mode

Examples of incorrect code for this rule with the default { "mode": "strict" } option:

/*eslint key-spacing: ["error", { "mode": "strict" }]*/

call({
    foobar: 42,
    bat:    2 * 2
});

Examples of correct code for this rule with the default { "mode": "strict" } option:

/*eslint key-spacing: ["error", { "mode": "strict" }]*/

call({
    foobar: 42,
    bat: 2 * 2
});

Examples of correct code for this rule with the { "mode": "minimum" } option:

/*eslint key-spacing: ["error", { "mode": "minimum" }]*/

call({
    foobar: 42,
    bat:    2 * 2
});

align

Examples of incorrect code for this rule with the { "align": "value" } option:

/*eslint key-spacing: ["error", { "align": "value" }]*/

var obj = {
    a: value,
    bcde:  42,
    fg :   foo()
};

Examples of correct code for this rule with the { "align": "value" } option:

/*eslint key-spacing: ["error", { "align": "value" }]*/

var obj = {
    a:    value,
    bcde: 42,

    fg: foo(),
    h:  function() {
        return this.a;
    },
    ijkl: 'Non-consecutive lines form a new group'
};

var obj = { a: "foo", longPropertyName: "bar" };

Examples of incorrect code for this rule with the { "align": "colon" } option:

/*eslint key-spacing: ["error", { "align": "colon" }]*/

call({
    foobar: 42,
    bat:    2 * 2
});

Examples of correct code for this rule with the { "align": "colon" } option:

/*eslint key-spacing: ["error", { "align": "colon" }]*/

call({
    foobar: 42,
    bat   : 2 * 2
});

align

The align option can take additional configuration through the beforeColon, afterColon, mode, and on options.

If align is defined as an object, but not all of the parameters are provided, undefined parameters will default to the following:

// Defaults
align: {
    "beforeColon": false,
    "afterColon": true,
    "on": "colon",
    "mode": "strict"
}

Examples of correct code for this rule with sample { "align": { } } options:

/*eslint key-spacing: ["error", {
    "align": {
        "beforeColon": true,
        "afterColon": true,
        "on": "colon"
    }
}]*/

var obj = {
    "one"   : 1,
    "seven" : 7
}

/*eslint key-spacing: ["error", {
    "align": {
        "beforeColon": false,
        "afterColon": false,
        "on": "value"
    }
}]*/

var obj = {
    "one":  1,
    "seven":7
}

align and multiLine

The multiLine and align options can differ, which allows for fine-tuned control over the key-spacing of your files. align will not inherit from multiLine if align is configured as an object.

multiLine is used any time an object literal spans multiple lines. The align configuration is used when there is a group of properties in the same object. For example:

var myObj = {
  key1: 1, // uses multiLine

  key2: 2, // uses align (when defined)
  key3: 3, // uses align (when defined)

  key4: 4 // uses multiLine
}

Examples of incorrect code for this rule with sample { "align": { }, "multiLine": { } } options:

/*eslint key-spacing: ["error", {
    "multiLine": {
        "beforeColon": false,
        "afterColon":true
    },
    "align": {
        "beforeColon": true,
        "afterColon": true,
        "on": "colon"
    }
}]*/

var obj = {
    "myObjectFunction": function() {
        // Do something
    },
    "one"             : 1,
    "seven"           : 7
}

Examples of correct code for this rule with sample { "align": { }, "multiLine": { } } options:

/*eslint key-spacing: ["error", {
    "multiLine": {
        "beforeColon": false,
        "afterColon": true

    },
    "align": {
        "beforeColon": true,
        "afterColon": true,
        "on": "colon"
    }
}]*/

var obj = {
    "myObjectFunction": function() {
        // Do something
        //
    }, // These are two separate groups, so no alignment between `myObjectFuction` and `one`
    "one"   : 1,
    "seven" : 7 // `one` and `seven` are in their own group, and therefore aligned
}

singleLine and multiLine

Examples of correct code for this rule with sample { "singleLine": { }, "multiLine": { } } options:

/*eslint "key-spacing": [2, {
    "singleLine": {
        "beforeColon": false,
        "afterColon": true
    },
    "multiLine": {
        "beforeColon": true,
        "afterColon": true,
        "align": "colon"
    }
}]*/
var obj = { one: 1, "two": 2, three: 3 };
var obj2 = {
    "two" : 2,
    three : 3
};

When Not To Use It

If you have another convention for property spacing that might not be consistent with the available options, or if you want to permit multiple styles concurrently you can safely disable this rule. Source: http://eslint.org/docs/rules/

  var markerData = markerDataLoader.getData();

Close

require let or const instead of var (no-var)

ECMAScript 6 allows programmers to create variables with block scope instead of function scope using the let and const keywords. Block scope is common in many other programming languages and helps programmers avoid mistakes such as:

var count = people.length;
var enoughFood = count > sandwiches.length;

if (enoughFood) {
    var count = sandwiches.length; // accidentally overriding the count variable
    console.log("We have " + count + " sandwiches for everyone. Plenty for all!");
}

// our count variable is no longer accurate
console.log("We have " + count + " people and " + sandwiches.length + " sandwiches!");

Rule Details

This rule is aimed at discouraging the use of var and encouraging the use of const or let instead.

Examples

Examples of incorrect code for this rule:

/*eslint no-var: "error"*/

var x = "y";
var CONFIG = {};

Examples of correct code for this rule:

/*eslint no-var: "error"*/
/*eslint-env es6*/

let x = "y";
const CONFIG = {};

When Not To Use It

In addition to non-ES6 environments, existing JavaScript projects that are beginning to introduce ES6 into their codebase may not want to apply this rule if the cost of migrating from var to let is too costly. Source: http://eslint.org/docs/rules/