eslint/docs/rules/multiline-ternary.md

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