arrow-spacing

Enforce consistent spacing before and after the arrow in arrow functions

This rule normalize style of spacing before/after an arrow function’s arrow(=>).

// { "before": true, "after": true } (a) => {} // { "before": false, "after": false } (a)=>{} 
1
2
3
4
5

Rule Details

This rule takes an object argument with before and after properties, each with a Boolean value.

The default configuration is { "before": true, "after": true }.

true means there should be one or more spaces and false means no spaces.

Examples of incorrect code for this rule with the default { "before": true, "after": true } option:

/*eslint arrow-spacing: "error"*/ ()=> {}; () =>{}; (a)=> {}; (a) =>{}; a =>a; a=> a; ()=> {'\n'}; () =>{'\n'}; 
1
2
3
4
5
6
7
8
9
10

Examples of correct code for this rule with the default { "before": true, "after": true } option:

/*eslint arrow-spacing: "error"*/ () => {}; (a) => {}; a => a; () => {'\n'}; 
1
2
3
4
5
6

Examples of incorrect code for this rule with the { "before": false, "after": false } option:

/*eslint arrow-spacing: ["error", { "before": false, "after": false }]*/ () =>{}; (a) => {}; ()=> {'\n'}; 
1
2
3
4
5

Examples of correct code for this rule with the { "before": false, "after": false } option:

/*eslint arrow-spacing: ["error", { "before": false, "after": false }]*/ ()=>{}; (a)=>{}; ()=>{'\n'}; 
1
2
3
4
5

Examples of incorrect code for this rule with the { "before": false, "after": true } option:

/*eslint arrow-spacing: ["error", { "before": false, "after": true }]*/ () =>{}; (a) => {}; ()=>{'\n'}; 
1
2
3
4
5

Examples of correct code for this rule with the { "before": false, "after": true } option:

/*eslint arrow-spacing: ["error", { "before": false, "after": true }]*/ ()=> {}; (a)=> {}; ()=> {'\n'}; 
1
2
3
4
5

Version

This rule was introduced in ESLint v1.0.0-rc-1.

Resources

• Rule source
• Tests source