HTMLMinifier is a highly configurable, well-tested, Javascript-based HTML minifier, with lint-like capabilities.
See corresponding blog post for all the gory details of how it works, description of each option, testing results and conclusions.
Test suite is available online.
Also see corresponding Ruby wrapper, and for Node.js, Grunt plugin, Gulp module, and Koa middleware wrapper.
How does HTMLMinifier compare to other solutions — HTML Minifier from Will Peavy (1st result in google search for "html minifier") as well as htmlcompressor.com and minimize?
| Site | Original size (KB) | HTMLMinifier | minimize | Will Peavy | htmlcompressor.com |
|---|---|---|---|---|---|
| HTMLMinifier page | 48.8 | 37.3 | 41.8 | 43.3 | 41.9 |
| ES6 table | 117.9 | 79.9 | 94.1 | 92 | 91.9 |
| MSN | 156.6 | 133 | 137.7 | 145 | 138.3 |
| Stackoverflow | 200.4 | 159.5 | 165.1 | 168.3 | 163.3 |
| Amazon | 245.9 | 206.3 | 234.1 | 225 | 218.5 |
| Wikipedia | 401.4 | 380.6 | 386.6 | 396.3 | n/a |
| Eloquent Javascript | 869.5 | 830 | 838 | 872 | n/a |
| Option | Description | Default |
|---|---|---|
removeComments |
Strip HTML comments | false |
removeCommentsFromCDATA |
Strip HTML comments from scripts and styles | false |
removeCDATASectionsFromCDATA |
Remove CDATA sections from script and style elements | false |
collapseWhitespace |
Collapse white space that contributes to text nodes in a document tree. | false |
conservativeCollapse |
Always collapse to 1 space (never remove it entirely). Must be used in conjunction with collapseWhitespace=true |
false |
preserveLineBreaks |
Always collapse to 1 line break (never remove it entirely) when whitespace between tags include a line break. Must be used in conjunction with collapseWhitespace=true |
false |
collapseBooleanAttributes |
Omit attribute values from boolean attributes | false |
removeAttributeQuotes |
Remove quotes around attributes when possible. | false |
removeRedundantAttributes |
Remove attributes when value matches default. | false |
preventAttributesEscaping |
Prevents the escaping of the values of attributes. | false |
useShortDoctype |
Replaces the doctype with the short (HTML5) doctype | false |
removeEmptyAttributes |
Remove all attributes with whitespace-only values | false |
removeScriptTypeAttributes |
Remove type="text/javascript" from script tags. Other type attribute values are left intact. |
false |
removeStyleLinkTypeAttributes |
Remove type="text/css" from style and link tags. Other type attribute values are left intact. |
false |
removeOptionalTags |
Remove unrequired tags | false |
removeEmptyElements |
Remove all elements with empty contents | false |
lint |
Toggle linting | false |
keepClosingSlash |
Keep the trailing slash on singleton elements | false |
caseSensitive |
Treat attributes in case sensitive manner (useful for custom HTML tags.) | false |
minifyJS |
Minify Javascript in script elements and on* attributes (uses UglifyJS) | false (could be true, false, Object (options)) |
minifyCSS |
Minify CSS in style elements and style attributes (uses clean-css) | false (could be true, false, Object (options)) |
minifyURLs |
Minify URLs in various attributes (uses relateurl) | false (could be Object (options)) |
ignoreCustomComments |
Array of regex'es that allow to ignore certain comments, when matched | [ ] |
ignoreCustomFragments |
Array of regex'es that allow to ignore certain fragments, when matched (e.g. <?php ... ?>, {{ ... }}, etc.) |
[ ] |
processScripts |
Array of strings corresponding to types of script elements to process through minifier (e.g. text/ng-template, text/x-handlebars-template, etc.) |
[ ] |
maxLineLength |
Specify a maximum line length. Compressed output will be split by newlines at valid HTML split-points. | |
customAttrAssign |
Arrays of regex'es that allow to support custom attribute assign expressions (e.g. '<div flex?="{{mode != cover}}"></div>') |
[ ] |
customAttrSurround |
Arrays of regex'es that allow to support custom attribute surround expressions (e.g. <input {{#if value}}checked="checked"{{/if}}>) |
[ ] |
customAttrCollapse |
Regex that specifies custom attribute to strip newlines from (e.g. /ng\-class/) |
|
quoteCharacter |
Type of quote to use for attribute values (' or ") | " |
If you have chunks of markup you would like preserved, you can wrap them <!-- htmlmin:ignore -->.
SVG tags are automatically recognized, and when they are minified, both case-sensitivity and closing-slashes are preserved, regardless of the minification settings used for the rest of the file.
HTMLMinifier can't work with invalid or partial chunks of markup. This is because it parses markup into a tree structure, then modifies it (removing anything that was specified for removal, ignoring anything that was specified to be ingored, etc.), then it creates a markup out of that tree and returns it.
Input markup (e.g. <p id="">foo)
↓
Internal representation of markup in a form of tree (e.g. {tag: "p", attr: "id", children: ["foo"] })
↓
Transformation of internal representation (e.g. removal of "id" attribute)
↓
Output of resulting markup (e.g. <p>foo</p>)
HTMLMinifier can't know that original markup was only half of the tree; it does its best to try to parse it as a full tree and it loses information about tree being malformed or partial in the beginning. As a result, it can't create a partial/malformed tree at the time of the output.
From NPM for use as a command line app:
npm install html-minifier -gFrom NPM for programmatic use:
npm install html-minifierFrom Git:
git clone git://github.com/kangax/html-minifier.git
cd html-minifier
npm link .For command line usage please see html-minifier --help
var minify = require('html-minifier').minify;
var result = minify('<p title="blah" id="moo">foo</p>', {
removeAttributeQuotes: true
});
result; // '<p title=blah id=moo>foo</p>'Benchmarks for minified HTML:
node benchmark.js