no-invalid-entity

Disallow use of invalid HTML entities.

Rule Details

This rule disallows the use of invalid HTML entities in your markup. HTML entities are special codes used to represent characters with specific meanings in HTML, such as < (<) or & (&). Invalid entities—such as typos, undefined entities, or malformed numeric references—can be silently ignored by browsers, leading to rendering issues or confusion.

The rule validates both named entities (e.g.,  ) and numeric entities (e.g.,   for decimal or   for hexadecimal) against a list of valid entities defined in entities.json. An entity is considered invalid if:

  1. It is a named entity not found in entities.json (e.g., &nbsb; or &unknown;).
  2. It is a numeric entity with an invalid format (e.g., &#zzzz;).
  3. It is a numeric entity outside the valid Unicode range (0 to 0x10FFFF, e.g., �).

How to use

.eslintrc.js 
module.exports = {
  rules: {
    "@html-eslint/no-invalid-entity": "error",
  },
};

Examples

Incorrect Code 

<p>&nbsb;</p>        <!-- typo -->
<p>&unknown;</p>     <!-- undefined entity -->
<p>&#zzzz;</p>       <!-- invalid numeric reference -->

Correct Code 

<p>&lt; &gt; &amp; &nbsp; &#160; &#xA0;</p>

When Not To Use It

Disable this rule if you are intentionally using invalid entities for specific purposes, such as testing or non-standard rendering. Be aware that invalid entities may not render consistently across different browsers.