eslint/docs/src/rules/one-var-declaration-per-line.md

   1 ---
   2 title: one-var-declaration-per-line
   3 layout: doc
   4 rule_type: suggestion
   5 related_rules:
   6 - one-var
   7 ---
   8
   9
  10
  11 Some developers declare multiple var statements on the same line:
  12
  13 ```js
  14 var foo, bar, baz;
  15 ```
  16
  17 Others prefer to declare one var per line.
  18
  19 ```js
  20 var foo,
  21     bar,
  22     baz;
  23 ```
  24
  25 Keeping to one of these styles across a project's codebase can help with maintaining code consistency.
  26
  27 ## Rule Details
  28
  29 This rule enforces a consistent newlines around variable declarations. This rule ignores variable declarations inside `for` loop conditionals.
  30
  31 ## Options
  32
  33 This rule has a single string option:
  34
  35 * `"initializations"` (default) enforces a newline around variable initializations
  36 * `"always"` enforces a newline around variable declarations
  37
  38 ### initializations
  39
  40 Examples of **incorrect** code for this rule with the default `"initializations"` option:
  41
  42 ::: incorrect
  43
  44 ```js
  45 /*eslint one-var-declaration-per-line: ["error", "initializations"]*/
  46 /*eslint-env es6*/
  47
  48 var a, b, c = 0;
  49
  50 let a,
  51     b = 0, c;
  52 ```
  53
  54 :::
  55
  56 Examples of **correct** code for this rule with the default `"initializations"` option:
  57
  58 ::: correct
  59
  60 ```js
  61 /*eslint one-var-declaration-per-line: ["error", "initializations"]*/
  62 /*eslint-env es6*/
  63
  64 var a, b;
  65
  66 let a,
  67     b;
  68
  69 let a,
  70     b = 0;
  71 ```
  72
  73 :::
  74
  75 ### always
  76
  77 Examples of **incorrect** code for this rule with the `"always"` option:
  78
  79 ::: incorrect
  80
  81 ```js
  82 /*eslint one-var-declaration-per-line: ["error", "always"]*/
  83 /*eslint-env es6*/
  84
  85 var a, b;
  86
  87 let a, b = 0;
  88
  89 const a = 0, b = 0;
  90 ```
  91
  92 :::
  93
  94 Examples of **correct** code for this rule with the `"always"` option:
  95
  96 ::: correct
  97
  98 ```js
  99 /*eslint one-var-declaration-per-line: ["error", "always"]*/
 100 /*eslint-env es6*/
 101
 102 var a,
 103     b;
 104
 105 let a,
 106     b = 0;
 107 ```
 108
 109 :::