Introduce mergeStyles, refactor mergeScripts

CHANGELOG.md

@@ -4,6 +4,23 @@ As of version 5.0.0, all notable changes to HTML Minifier (HM) are documented in
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/), and the project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [5.1.0] - 2026-11-11
+
+### Fixed
+
+* Fixed `removeUnusedCSS` keeping style sheets of which nothing is used as written, unminified, where they held a word of ten or more lowercase letters (e.g., `background`; taken for a custom-fragment placeholder)
+* Fixed `mergeScripts` merging what only looks like scripts—text in `textarea` and `title` elements, comments, and markup kept with `htmlmin:ignore`—and losing code where a script holds `<!--<script>`, which browsers end only at a later `</script>` (e.g., `<script><!--<script></script><script></script></script>` lost `<script></script>`)
+* Fixed `mergeScripts` joining a script that ends in a custom fragment on one line with the next, which the fragment may comment out
+* Fixed `mergeScripts` dropping the attributes of scripts merged into another, whose own attributes then covered their code, too—which tools that rewrite pages in the browser or at the edge read (e.g., `data-cfasync="false"` for Cloudflare Rocket Loader, or `data-cookieconsent`)—scripts now merge only where their attributes match (other than a JavaScript `type`), and not where they have an `id`
+
+### Added
+
+* Added `mergeStyles` (part of the `comprehensive` preset) to merge consecutive `style` elements with compatible style sheets into one, which `minifyCSS` then minifies as one (e.g., `<style>a{color:red}</style><style>a{color:blue}</style>` becomes `<style>a{color:#00f}</style>`)
+
+### Changed
+
+* Made `mergeScripts` faster, as it merges what the minifier writes rather than scanning its output again
+
 ## [5.0.4] - 2026-11-11
 
 ### Fixed

README.md

@@ -161,7 +161,8 @@ Options can be used in config files (camelCase) or via CLI flags (kebab-case wit
 | `keepClosingSlash`<br>`--keep-closing-slash` | Keep the trailing slash on void elements and other start tags that carry one, and read it as closing the element | `false` |
 | `maxInputLength`<br>`--max-input-length` | Maximum input length to prevent ReDoS attacks (disabled by default) | `undefined` |
 | `maxLineLength`<br>`--max-line-length` | Specify a maximum line length; output will be split by newlines in tags only (between attributes or before a tag’s `>`), where they can’t change the page, so lines may run longer | `undefined` |
-| `mergeScripts`<br>`--merge-scripts` | Merge consecutive inline `script` elements into one (only merges compatible scripts with same `type`, matching `async`/`defer`/`nomodule`/`nonce`) | `false` |
+| `mergeScripts`<br>`--merge-scripts` | Merge consecutive `script` elements into one (only merges classic scripts whose attributes match, and none with an `id`) | `false` |
+| `mergeStyles`<br>`--merge-styles` | Merge consecutive `style` elements into one (only merges style sheets whose attributes match, and none with an `id`) | `false` |
 | `minifyCSS`<br>`--minify-css` | [Minify CSS](#css-minification) in `style` elements and attributes (uses [Lightning CSS](https://lightningcss.dev/)) | `false` (could be `true`, `Object`, `Function(text, type)`) |
 | `minifyJS`<br>`--minify-js` | [Minify JavaScript](#javascript-minification) in `script` elements and event attributes (uses [Terser](https://terser.org/) or [SWC](https://swc.rs/)) | `false` (could be `true`, `Object`, `Function(text, inline)`) |
 | `minifyJSON`<br>`--minify-json` | [Minify JSON](#json-minification) in `script` elements (e.g., `application/ld+json`, `importmap`, etc.) by removing whitespace | `false` |

backtest/html-minifier.config.json

@@ -32,6 +32,7 @@
   "maxInputLength": 0,
   "maxLineLength": 0,
   "mergeScripts": true,
+  "mergeStyles": true,
   "minifyCSS": true,
   "minifyJS": {
     "engine": "swc"

demo/default.js

@@ -92,6 +92,10 @@ const demoConfig = {
     label: 'Merge scripts',
     checked: true
   },
+  mergeStyles: {
+    label: 'Merge styles',
+    checked: true
+  },
   minifyCSS: {
     label: 'Minify CSS',
     checked: false,

html-minifier.schema.json

@@ -178,7 +178,11 @@
       "minimum": 0
     },
     "mergeScripts": {
-      "description": "Merge consecutive inline `script` elements into one",
+      "description": "Merge consecutive `script` elements into one",
+      "type": "boolean"
+    },
+    "mergeStyles": {
+      "description": "Merge consecutive `style` elements into one",
       "type": "boolean"
     },
     "minifyCSS": {

package.json

@@ -95,5 +95,5 @@
   },
   "type": "module",
   "types": "dist/types/htmlminifier.d.ts",
-  "version": "5.0.4"
+  "version": "5.1.0"
 }