JS.BASE.NO.MULTI.SPACES

Multiple spaces in a row that are not used for indentation are typically mistakes. For example:

if(foo  === "bar") {}

It's hard to tell, but there are two spaces between foo and ===. Multiple spaces such as this are generally frowned upon in favor of single spaces:

if(foo === "bar") {}

Rule Details

This rule aims to disallow multiple whitespace around logical expressions, conditional expressions, declarations, array elements, object properties, sequences and function parameters.

Examples of incorrect code for this rule:

/*eslint no-multi-spaces: "error"*/

var a =  1;

if(foo   === "bar") {}

a <<  b

var arr = [1,  2];

a ?  b: c

Examples of correct code for this rule:

/*eslint no-multi-spaces: "error"*/

var a = 1;

if(foo === "bar") {}

a << b

var arr = [1, 2];

a ? b: c

Options

This rule's configuration consists of an object with the following properties:

• "ignoreEOLComments": true (defaults to false) ignores multiple spaces before comments that occur at the end of lines
• "exceptions": { "Property": true } ("Property" is the only node specified by default) specifies nodes to ignore

ignoreEOLComments

Examples of incorrect code for this rule with the { "ignoreEOLComments": false } (default) option:

/*eslint no-multi-spaces: ["error", { ignoreEOLComments: false }]*/

var x = 5;      // comment
var x = 5;      /* multiline
 * comment
 */

Examples of correct code for this rule with the { "ignoreEOLComments": false } (default) option:

/*eslint no-multi-spaces: ["error", { ignoreEOLComments: false }]*/

var x = 5; // comment
var x = 5; /* multiline
 * comment
 */

Examples of correct code for this rule with the { "ignoreEOLComments": true } option:

/*eslint no-multi-spaces: ["error", { ignoreEOLComments: true }]*/

var x = 5; // comment
var x = 5;      // comment
var x = 5; /* multiline
 * comment
 */
var x = 5;      /* multiline
 * comment
 */

exceptions

To avoid contradictions with other rules that require multiple spaces, this rule has an exceptions option to ignore certain nodes.

This option is an object that expects property names to be AST node types as defined by ESTree (https://github.com/estree/estree). The easiest way to determine the node types for exceptions is to use AST Explorer (https://astexplorer.net/) with the espree parser.

Only the Property node type is ignored by default, because for the key-spacing rule some alignment options require multiple spaces in properties of object literals.

Examples of correct code for the default "exceptions": { "Property": true } option:

/*eslint no-multi-spaces: "error"*/
/*eslint key-spacing: ["error", { align: "value" }]*/

var obj = {
    first:  "first",
    second: "second"
};

Examples of incorrect code for the "exceptions": { "Property": false } option:

/*eslint no-multi-spaces: ["error", { exceptions: { "Property": false } }]*/
/*eslint key-spacing: ["error", { align: "value" }]*/

var obj = {
    first:  "first",
    second: "second"
};

Examples of correct code for the "exceptions": { "BinaryExpression": true } option:

/*eslint no-multi-spaces: ["error", { exceptions: { "BinaryExpression": true } }]*/

var a = 1  *  2;

Examples of correct code for the "exceptions": { "VariableDeclarator": true } option:

/*eslint no-multi-spaces: ["error", { exceptions: { "VariableDeclarator": true } }]*/

var someVar      = 'foo';
var someOtherVar = 'barBaz';

Examples of correct code for the "exceptions": { "ImportDeclaration": true } option:

/*eslint no-multi-spaces: ["error", { exceptions: { "ImportDeclaration": true } }]*/

import mod          from 'mod';
import someOtherMod from 'some-other-mod';

When Not To Use It

If you don't want to check and disallow multiple spaces, then you should turn this rule off.