eslint/docs/src/rules/multiline-ternary.md

   1 ---
   2 title: multiline-ternary
   3 rule_type: layout
   4 related_rules:
   5 - operator-linebreak
   6 ---
   7
   8
   9
  10 JavaScript allows operands of ternary expressions to be separated by newlines, which can improve the readability of your program.
  11
  12 For example:
  13
  14 ```js
  15 var foo = bar > baz ? value1 : value2;
  16 ```
  17
  18 The above can be rewritten as the following to improve readability and more clearly delineate the operands:
  19
  20 ```js
  21 var foo = bar > baz ?
  22     value1 :
  23     value2;
  24 ```
  25
  26 ## Rule Details
  27
  28 This rule enforces or disallows newlines between operands of a ternary expression.
  29 Note: The location of the operators is not enforced by this rule. Please see the [operator-linebreak](operator-linebreak) rule if you are interested in enforcing the location of the operators themselves.
  30
  31 ## Options
  32
  33 This rule has a string option:
  34
  35 * `"always"` (default) enforces newlines between the operands of a ternary expression.
  36 * `"always-multiline"` enforces newlines between the operands of a ternary expression if the expression spans multiple lines.
  37 * `"never"` disallows newlines between the operands of a ternary expression.
  38
  39 ### always
  40
  41 This is the default option.
  42
  43 Examples of **incorrect** code for this rule with the `"always"` option:
  44
  45 ::: incorrect
  46
  47 ```js
  48 /*eslint multiline-ternary: ["error", "always"]*/
  49
  50 foo > bar ? value1 : value2;
  51
  52 foo > bar ? value :
  53     value2;
  54
  55 foo > bar ?
  56     value : value2;
  57 ```
  58
  59 :::
  60
  61 Examples of **correct** code for this rule with the `"always"` option:
  62
  63 ::: correct
  64
  65 ```js
  66 /*eslint multiline-ternary: ["error", "always"]*/
  67
  68 foo > bar ?
  69     value1 :
  70     value2;
  71
  72 foo > bar ?
  73     (baz > qux ?
  74         value1 :
  75         value2) :
  76     value3;
  77 ```
  78
  79 :::
  80
  81 ### always-multiline
  82
  83 Examples of **incorrect** code for this rule with the `"always-multiline"` option:
  84
  85 ::: incorrect
  86
  87 ```js
  88 /*eslint multiline-ternary: ["error", "always-multiline"]*/
  89
  90 foo > bar ? value1 :
  91     value2;
  92
  93 foo > bar ?
  94     value1 : value2;
  95
  96 foo > bar &&
  97     bar > baz ? value1 : value2;
  98 ```
  99
 100 :::
 101
 102 Examples of **correct** code for this rule with the `"always-multiline"` option:
 103
 104 ::: correct
 105
 106 ```js
 107 /*eslint multiline-ternary: ["error", "always-multiline"]*/
 108
 109 foo > bar ? value1 : value2;
 110
 111 foo > bar ?
 112     value1 :
 113     value2;
 114
 115 foo > bar ?
 116     (baz > qux ? value1 : value2) :
 117     value3;
 118
 119 foo > bar ?
 120     (baz > qux ?
 121         value1 :
 122         value2) :
 123     value3;
 124
 125 foo > bar &&
 126     bar > baz ?
 127         value1 :
 128         value2;
 129 ```
 130
 131 :::
 132
 133 ### never
 134
 135 Examples of **incorrect** code for this rule with the `"never"` option:
 136
 137 ::: incorrect
 138
 139 ```js
 140 /*eslint multiline-ternary: ["error", "never"]*/
 141
 142 foo > bar ? value :
 143     value2;
 144
 145 foo > bar ?
 146     value : value2;
 147
 148 foo >
 149     bar ?
 150     value1 :
 151     value2;
 152 ```
 153
 154 :::
 155
 156 Examples of **correct** code for this rule with the `"never"` option:
 157
 158 ::: correct
 159
 160 ```js
 161 /*eslint multiline-ternary: ["error", "never"]*/
 162
 163 foo > bar ? value1 : value2;
 164
 165 foo > bar ? (baz > qux ? value1 : value2) : value3;
 166
 167 foo > bar ? (
 168     baz > qux ? value1 : value2
 169 ) : value3;
 170 ```
 171
 172 :::
 173
 174 ## When Not To Use It
 175
 176 You can safely disable this rule if you do not have any strict conventions about whether the operands of a ternary expression should be separated by newlines.
 177
 178 ## Compatibility
 179
 180 * **JSCS**: [requireMultiLineTernary](https://jscs-dev.github.io/rule/requireMultiLineTernary)