eslint/docs/rules/arrow-spacing.md

   1 # Require space before/after arrow function's arrow (arrow-spacing)
   2
   3 This rule normalize style of spacing before/after an arrow function's arrow(`=>`).
   4
   5 ```js
   6 /*eslint-env es6*/
   7
   8 // { "before": true, "after": true }
   9 (a) => {}
  10
  11 // { "before": false, "after": false }
  12 (a)=>{}
  13 ```
  14
  15 ## Rule Details
  16
  17 This rule takes an object argument with `before` and `after` properties, each with a Boolean value.
  18
  19 The default configuration is `{ "before": true, "after": true }`.
  20
  21 `true` means there should be **one or more spaces** and `false` means **no spaces**.
  22
  23 Examples of **incorrect** code for this rule with the default `{ "before": true, "after": true }` option:
  24
  25 ```js
  26 /*eslint arrow-spacing: "error"*/
  27 /*eslint-env es6*/
  28
  29 ()=> {};
  30 () =>{};
  31 (a)=> {};
  32 (a) =>{};
  33 a =>a;
  34 a=> a;
  35 ()=> {'\n'};
  36 () =>{'\n'};
  37 ```
  38
  39 Examples of **correct** code for this rule with the default `{ "before": true, "after": true }` option:
  40
  41 ```js
  42 /*eslint arrow-spacing: "error"*/
  43 /*eslint-env es6*/
  44
  45 () => {};
  46 (a) => {};
  47 a => a;
  48 () => {'\n'};
  49 ```
  50
  51 Examples of **incorrect** code for this rule with the `{ "before": false, "after": false }` option:
  52
  53 ```js
  54 /*eslint arrow-spacing: ["error", { "before": false, "after": false }]*/
  55 /*eslint-env es6*/
  56
  57 () =>{};
  58 (a) => {};
  59 ()=> {'\n'};
  60 ```
  61
  62 Examples of **correct** code for this rule with the `{ "before": false, "after": false }` option:
  63
  64 ```js
  65 /*eslint arrow-spacing: ["error", { "before": false, "after": false }]*/
  66 /*eslint-env es6*/
  67
  68 ()=>{};
  69 (a)=>{};
  70 ()=>{'\n'};
  71 ```
  72
  73 Examples of **incorrect** code for this rule with the `{ "before": false, "after": true }` option:
  74
  75 ```js
  76 /*eslint arrow-spacing: ["error", { "before": false, "after": true }]*/
  77 /*eslint-env es6*/
  78
  79 () =>{};
  80 (a) => {};
  81 ()=>{'\n'};
  82 ```
  83
  84 Examples of **correct** code for this rule with the `{ "before": false, "after": true }` option:
  85
  86 ```js
  87 /*eslint arrow-spacing: ["error", { "before": false, "after": true }]*/
  88 /*eslint-env es6*/
  89
  90 ()=> {};
  91 (a)=> {};
  92 ()=> {'\n'};
  93 ```