comma-spacing.md

title	rule_type	related_rules	further_reading
comma-spacing	layout	array-bracket-spacing comma-style object-curly-spacing space-in-brackets space-in-parens space-infix-ops space-after-keywords space-unary-ops space-return-throw-case	https://www.crockford.com/code.html https://dojotoolkit.org/reference-guide/1.9/developer/styleguide.html

This rule was deprecated in ESLint v8.53.0. Please use the corresponding rule in @stylistic/eslint-plugin-js.

Spacing around commas improves readability of a list of items. Although most of the style guidelines for languages prescribe adding a space after a comma and not before it, it is subjective to the preferences of a project.

var foo = 1, bar = 2;
var foo = 1 ,bar = 2;

Rule Details

This rule enforces consistent spacing before and after commas in variable declarations, array literals, object literals, function parameters, and sequences.

This rule does not apply in either of the following cases:

• between two commas
• between opening bracket [ and comma, to avoid conflicts with the array-bracket-spacing rule
• between comma and closing bracket ], to avoid conflicts with the array-bracket-spacing rule
• between comma and closing brace }, to avoid conflicts with the object-curly-spacing rule
• between comma and closing parentheses ), to avoid conflicts with the space-in-parens rule

Options

This rule has an object option:

• "before": false (default) disallows spaces before commas
• "before": true requires one or more spaces before commas
• "after": true (default) requires one or more spaces after commas
• "after": false disallows spaces after commas

after

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

:::incorrect

/*eslint comma-spacing: ["error", { "before": false, "after": true }]*/

var foo = 1 ,bar = 2;
var arr = [1 , 2];
var obj = {"foo": "bar" ,"baz": "qur"};
foo(a ,b);
new Foo(a ,b);
function baz(a ,b){}
a ,b

:::

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

:::correct

/*eslint comma-spacing: ["error", { "before": false, "after": true }]*/

var foo = 1, bar = 2
    , baz = 3;
var arr = [1, 2];
var arr = [1,, 3]
var obj = {"foo": "bar", "baz": "qur"};
foo(a, b);
new Foo(a, b);
function qur(a, b){}
a, b

:::

Additional examples of correct code for this rule with the default { "before": false, "after": true } options:

:::correct

/*eslint comma-spacing: ["error", { "before": false, "after": true }]*/

// this rule does not enforce spacing between two commas
var arr = [
    ,,
    , ,
];

// this rule does not enforce spacing after `[` and before `]`
var arr = [,];
var arr = [ , ];
var arr = [a, b,];
[,] = arr;
[ , ] = arr;
[a, b,] = arr;

// this rule does not enforce spacing before `}`
var obj = {x, y,};
var {z, q,} = obj;
import {foo, bar,} from "mod";

// this rule does not enforce spacing before `)`
foo(a, b,)

:::

before

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

:::incorrect

/*eslint comma-spacing: ["error", { "before": true, "after": false }]*/

var foo = 1, bar = 2;
var arr = [1 , 2];
var obj = {"foo": "bar", "baz": "qur"};
new Foo(a,b);
function baz(a,b){}
a, b

:::

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

:::correct

/*eslint comma-spacing: ["error", { "before": true, "after": false }]*/

var foo = 1 ,bar = 2 ,
    baz = true;
var arr = [1 ,2];
var arr = [1 ,,3]
var obj = {"foo": "bar" ,"baz": "qur"};
foo(a ,b);
new Foo(a ,b);
function qur(a ,b){}
a ,b

:::

When Not To Use It

If your project will not be following a consistent comma-spacing pattern, turn this rule off.