---
title: key-spacing - Rules
layout: doc
edit_link: https://github.com/eslint/eslint/edit/master/docs/rules/key-spacing.md
---
<!-- Note: No pull requests accepted for this file. See README.md in the root directory for details. -->

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

(fixable) The `--fix` option on the [command line](../user-guide/command-line-interface#fix) can automatically fix some of the problems reported by this rule.

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) | true`
    * `false`: disallows spaces between the key and the colon in object literals.
    * `true`: requires at least one space between the key and the colon in object literals.
* `"afterColon": true (default) | false`
    * `true`: requires at least one space between the colon and the value in object literals.
    * `false`: disallows spaces between the colon and the value in object literals.
* `"mode": "strict" (default) | "minimum"`
    * `"strict"`: enforces exactly one space before or after colons in object literals.
    * `"minimum"`: enforces one or more spaces before or after colons in object literals.
* `"align": "value" | "colon"`
    * `"value"`: enforces horizontal alignment of values in object literals.
    * `"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:

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

var obj = { "foo" : 42 };
```

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

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

var obj = { "foo": 42 };
```

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

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

var obj = { "foo": 42 };
```

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

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

var obj = { "foo" : 42 };
```

### afterColon

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

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

var obj = { "foo":42 };
```

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

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

var obj = { "foo": 42 };
```

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

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

var obj = { "foo": 42 };
```

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

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

var obj = { "foo":42 };
```

### mode

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

```js
/*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:

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

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

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

```js
/*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:

```js
/*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:

```js
/*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:

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

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

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

```js
/*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:

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

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

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

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

```js
/*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:

```javascript
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:

```js
/*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:

```js
/*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:

```js
/*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.

## Version

This rule was introduced in ESLint 0.9.0.

## Resources

* [Rule source](https://github.com/eslint/eslint/tree/master/lib/rules/key-spacing.js)
* [Documentation source](https://github.com/eslint/eslint/tree/master/docs/rules/key-spacing.md)
