eslint/docs/src/rules/no-multi-spaces.md

   1 ---
   2 title: no-multi-spaces
   3 layout: doc
   4 rule_type: layout
   5 related_rules:
   6 - key-spacing
   7 - space-infix-ops
   8 - space-in-brackets
   9 - space-in-parens
  10 - space-after-keywords
  11 - space-unary-ops
  12 - space-return-throw-case
  13 ---
  14
  15
  16
  17 Multiple spaces in a row that are not used for indentation are typically mistakes. For example:
  18
  19 ```js
  20
  21 if(foo  === "bar") {}
  22
  23 ```
  24
  25 It's hard to tell, but there are two spaces between `foo` and `===`. Multiple spaces such as this are generally frowned upon in favor of single spaces:
  26
  27 ```js
  28
  29 if(foo === "bar") {}
  30
  31 ```
  32
  33 ## Rule Details
  34
  35 This rule aims to disallow multiple whitespace around logical expressions, conditional expressions, declarations, array elements, object properties, sequences and function parameters.
  36
  37 Examples of **incorrect** code for this rule:
  38
  39 ::: incorrect
  40
  41 ```js
  42 /*eslint no-multi-spaces: "error"*/
  43
  44 var a =  1;
  45
  46 if(foo   === "bar") {}
  47
  48 a <<  b
  49
  50 var arr = [1,  2];
  51
  52 a ?  b: c
  53 ```
  54
  55 :::
  56
  57 Examples of **correct** code for this rule:
  58
  59 ::: correct
  60
  61 ```js
  62 /*eslint no-multi-spaces: "error"*/
  63
  64 var a = 1;
  65
  66 if(foo === "bar") {}
  67
  68 a << b
  69
  70 var arr = [1, 2];
  71
  72 a ? b: c
  73 ```
  74
  75 :::
  76
  77 ## Options
  78
  79 This rule's configuration consists of an object with the following properties:
  80
  81 * `"ignoreEOLComments": true` (defaults to `false`) ignores multiple spaces before comments that occur at the end of lines
  82 * `"exceptions": { "Property": true }` (`"Property"` is the only node specified by default) specifies nodes to ignore
  83
  84 ### ignoreEOLComments
  85
  86 Examples of **incorrect** code for this rule with the `{ "ignoreEOLComments": false }` (default) option:
  87
  88 ::: incorrect
  89
  90 ```js
  91 /*eslint no-multi-spaces: ["error", { ignoreEOLComments: false }]*/
  92
  93 var x = 5;      // comment
  94 var x = 5;      /* multiline
  95  * comment
  96  */
  97 ```
  98
  99 :::
 100
 101 Examples of **correct** code for this rule with the `{ "ignoreEOLComments": false }` (default) option:
 102
 103 ::: correct
 104
 105 ```js
 106 /*eslint no-multi-spaces: ["error", { ignoreEOLComments: false }]*/
 107
 108 var x = 5; // comment
 109 var x = 5; /* multiline
 110  * comment
 111  */
 112 ```
 113
 114 :::
 115
 116 Examples of **correct** code for this rule with the `{ "ignoreEOLComments": true }` option:
 117
 118 ::: correct
 119
 120 ```js
 121 /*eslint no-multi-spaces: ["error", { ignoreEOLComments: true }]*/
 122
 123 var x = 5; // comment
 124 var x = 5;      // comment
 125 var x = 5; /* multiline
 126  * comment
 127  */
 128 var x = 5;      /* multiline
 129  * comment
 130  */
 131 ```
 132
 133 :::
 134
 135 ### exceptions
 136
 137 To avoid contradictions with other rules that require multiple spaces, this rule has an `exceptions` option to ignore certain nodes.
 138
 139 This option is an object that expects property names to be AST node types as defined by [ESTree](https://github.com/estree/estree). The easiest way to determine the node types for `exceptions` is to use [AST Explorer](https://astexplorer.net/) with the espree parser.
 140
 141 Only the `Property` node type is ignored by default, because for the [key-spacing](key-spacing) rule some alignment options require multiple spaces in properties of object literals.
 142
 143 Examples of **correct** code for the default `"exceptions": { "Property": true }` option:
 144
 145 ::: correct
 146
 147 ```js
 148 /*eslint no-multi-spaces: "error"*/
 149 /*eslint key-spacing: ["error", { align: "value" }]*/
 150
 151 var obj = {
 152     first:  "first",
 153     second: "second"
 154 };
 155 ```
 156
 157 :::
 158
 159 Examples of **incorrect** code for the `"exceptions": { "Property": false }` option:
 160
 161 ::: incorrect
 162
 163 ```js
 164 /*eslint no-multi-spaces: ["error", { exceptions: { "Property": false } }]*/
 165 /*eslint key-spacing: ["error", { align: "value" }]*/
 166
 167 var obj = {
 168     first:  "first",
 169     second: "second"
 170 };
 171 ```
 172
 173 :::
 174
 175 Examples of **correct** code for the `"exceptions": { "BinaryExpression": true }` option:
 176
 177 ::: correct
 178
 179 ```js
 180 /*eslint no-multi-spaces: ["error", { exceptions: { "BinaryExpression": true } }]*/
 181
 182 var a = 1  *  2;
 183 ```
 184
 185 :::
 186
 187 Examples of **correct** code for the `"exceptions": { "VariableDeclarator": true }` option:
 188
 189 ::: correct
 190
 191 ```js
 192 /*eslint no-multi-spaces: ["error", { exceptions: { "VariableDeclarator": true } }]*/
 193
 194 var someVar      = 'foo';
 195 var someOtherVar = 'barBaz';
 196 ```
 197
 198 :::
 199
 200 Examples of **correct** code for the `"exceptions": { "ImportDeclaration": true }` option:
 201
 202 ::: correct
 203
 204 ```js
 205 /*eslint no-multi-spaces: ["error", { exceptions: { "ImportDeclaration": true } }]*/
 206
 207 import mod          from 'mod';
 208 import someOtherMod from 'some-other-mod';
 209 ```
 210
 211 :::
 212
 213 ## When Not To Use It
 214
 215 If you don't want to check and disallow multiple spaces, then you should turn this rule off.