eslint-plugin-mark

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no-irregular-whitespace

✅ Recommended ⭐ CommonMark 🌟 GFM

🔗 Rule Source 🔗 Test Source

Disallow irregular whitespace.

Overview ​

Invalid or irregular whitespace can cause issues with Markdown 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.

A simple fix for this problem could be to rewrite the offending line from scratch. This might also be a problem introduced by the text editor: if rewriting the line does not fix it, try using a different editor.

Known issues these spaces cause:

  • Ogham Space Mark
    • Is a valid token separator, but is rendered as a visible glyph in most typefaces, which may be misleading in source code.
  • Mongolian Vowel Separator
    • Is no longer considered a space separator since Unicode 6.3. It could result in a error in Markdown parsers.
  • Line Separator and Paragraph Separator
    • Can cause issues with Markdown parsers that expect traditional line breaks (\n or \r\n). Many Markdown implementations may not properly recognize these as line terminators, leading to incorrectly formatted content or rendering problems.
  • Zero Width Space
    • Is NOT considered a separator for tokens.
    • Is NOT shown in modern browsers making code repository software expected to resolve the visualization.

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:

txt
\u000B - Line Tabulation (\v) - <VT>
\u000C - Form Feed (\f) - <FF>
\u00A0 - No-Break Space - <NBSP>
\u0085 - Next Line - <NEL>
\u1680 - Ogham Space Mark - <OGSP>
\u180E - Mongolian Vowel Separator - <MVS>
\ufeff - Zero Width No-Break Space - <BOM>
\u2000 - En Quad - <NQSP>
\u2001 - Em Quad - <MQSP>
\u2002 - En Space - <ENSP>
\u2003 - Em Space - <EMSP>
\u2004 - Three-Per-Em - <THPMSP> - <3/MSP>
\u2005 - Four-Per-Em - <FPMSP> - <4/MSP>
\u2006 - Six-Per-Em - <SPMSP> - <6/MSP>
\u2007 - Figure Space - <FSP>
\u2008 - Punctuation Space - <PUNCSP>
\u2009 - Thin Space - <THSP>
\u200A - Hair Space - <HSP>
\u200B - Zero Width Space - <ZWSP>
\u2028 - Line Separator - <LS> - <LSEP>
\u2029 - Paragraph Separator - <PS> - <PSEP>
\u202F - Narrow No-Break Space - <NNBSP>
\u205f - Medium Mathematical Space - <MMSP>
\u3000 - Ideographic Space - <IDSP>

Options ​

js
'mark/no-irregular-whitespace': ['error', {
  skipCode: true,
  skipInlineCode: true,
}]

skipCode ​

Default: true

true allows any irregular whitespace in code blocks.

skipInlineCode ​

Default: true

true allows any irregular whitespace in inline code.

When Not To Use It ​

If you decide that you wish to use whitespace other than tabs and spaces outside of strings in your document.

AST ​

This rule applies to the entire document, specifically to the Root node.

Prior Art ​