no-irregular-whitespace
disallow irregular whitespace (no-irregular-whitespace)
The "extends": "eslint:recommended" property in a configuration file enables this rule.
Invalid or irregular whitespace causes issues with ECMAScript 5 parsers and also makes code harder to debug in a similar nature to mixed tabs and spaces.
Various whitespace characters can be inputted by programmers by mistake for example from copying or keyboard shortcuts. Pressing Alt + Space on macOS adds in a non breaking space character for example.
Known issues these spaces cause:
- Zero Width Space
Rule Details
This rule is aimed at catching invalid whitespace that is not a normal tab and space. Some of these characters may cause issues in modern browsers and others will be a debugging issue to spot.
This rule disallows the following characters except where the options allow:
\u000B - Line Tabulation (\v) - <VT>
\u000C - Form Feed (\f) - <FF>
\u00A0 - No-Break Space - <NBSP>
\u0085 - Next Line
\u1680 - Ogham Space Mark
\u180E - Mongolian Vowel Separator - <MVS>
\ufeff - Zero Width No-Break Space - <BOM>
\u2000 - En Quad
\u2001 - Em Quad
\u2002 - En Space - <ENSP>
\u2003 - Em Space - <EMSP>
\u2004 - Tree-Per-Em
\u2005 - Four-Per-Em
\u2006 - Six-Per-Em
\u2007 - Figure Space
\u2008 - Punctuation Space - <PUNCSP>
\u2009 - Thin Space
\u200A - Hair Space
\u200B - Zero Width Space - <ZWSP>
\u2028 - Line Separator
\u2029 - Paragraph Separator
\u202F - Narrow No-Break Space
\u205f - Medium Mathematical Space
\u3000 - Ideographic Space
Options
This rule has an object option for exceptions:
"skipStrings": true(default) allows any whitespace characters in string literals
skipStrings
Examples of incorrect code for this rule with the default { "skipStrings": true } option:
/*eslint no-irregular-whitespace: "error"*/
function thing() /*<NBSP>*/{
return 'test';
}
function thing( /*<NBSP>*/){
return 'test';
}
function thing /*<NBSP>*/(){
return 'test';
}
function thing/*<MVS>*/(){
return 'test';
}
function thing() {
return 'test'; /*<ENSP>*/
}
function thing() {
return 'test'; /*<NBSP>*/
}
function thing() {
// Description <NBSP>: some descriptive text
}
/*
Description <NBSP>: some descriptive text
*/
function thing() {
return / <NBSP>regexp/;
}
/*eslint-env es6*/
function thing() {
return `template <NBSP>string`;
}
Examples of correct code for this rule with the default { "skipStrings": true } option:
/*eslint no-irregular-whitespace: "error"*/
function thing() {
return ' <NBSP>thing';
}
function thing() {
return '<ZWSP>thing';
}
function thing() {
return 'th <NBSP>ing';
}
skipComments
Examples of additional correct code for this rule with the { "skipComments": true } option:
/*eslint no-irregular-whitespace: ["error", { "skipComments": true }]*/
function thing() {
// Description <NBSP>: some descriptive text
}
/*
Description <NBSP>: some descriptive text
*/
skipRegExps
Examples of additional correct code for this rule with the { "skipRegExps": true } option:
/*eslint no-irregular-whitespace: ["error", { "skipRegExps": true }]*/
function thing() {
return / <NBSP>regexp/;
}
skipTemplates
Examples of additional correct code for this rule with the { "skipTemplates": true } option:
/*eslint no-irregular-whitespace: ["error", { "skipTemplates": true }]*/
/*eslint-env es6*/
function thing() {
return `template <NBSP>string`;
}
When Not To Use It
If you decide that you wish to use whitespace other than tabs and spaces outside of strings in your application.
Further Reading
- ECMA whitespace
Version
This rule was introduced in ESLint 0.9.0.
Resources
© JS Foundation and other contributors
Licensed under the MIT License.
