# HTMLMinifier [![NPM version](https://img.shields.io/npm/v/html-minifier.svg)](https://www.npmjs.com/package/html-minifier) [![Build Status](https://img.shields.io/travis/kangax/html-minifier.svg)](https://travis-ci.org/kangax/html-minifier) [![Dependency Status](https://img.shields.io/david/kangax/html-minifier.svg)](https://david-dm.org/kangax/html-minifier) [![devDependency Status](https://img.shields.io/david/dev/kangax/html-minifier.svg)](https://david-dm.org/kangax/html-minifier?type=dev) [![Gitter](https://img.shields.io/gitter/room/kangax/html-minifier.svg)](https://gitter.im/kangax/html-minifier) [HTMLMinifier](http://kangax.github.io/html-minifier/) is a highly **configurable**, **well-tested**, JavaScript-based HTML minifier. See [corresponding blog post](http://perfectionkills.com/experimenting-with-html-minifier/) for all the gory details of [how it works](http://perfectionkills.com/experimenting-with-html-minifier/#how_it_works), [description of each option](http://perfectionkills.com/experimenting-with-html-minifier/#options), [testing results](http://perfectionkills.com/experimenting-with-html-minifier/#field_testing) and [conclusions](http://perfectionkills.com/experimenting-with-html-minifier/#cost_and_benefits). [Test suite is available online](http://kangax.github.io/html-minifier/tests/). Also see corresponding [Ruby wrapper](https://github.com/stereobooster/html_minifier), and for Node.js, [Grunt plugin](https://github.com/gruntjs/grunt-contrib-htmlmin), [Gulp module](https://github.com/jonschlinkert/gulp-htmlmin), [Koa middleware wrapper](https://github.com/koajs/html-minifier) and [Express middleware wrapper](https://github.com/melonmanchan/express-minify-html). For lint-like capabilities take a look at [HTMLLint](https://github.com/kangax/html-lint). ## Minification comparison How does HTMLMinifier compare to other solutions — [HTML Minifier from Will Peavy](http://www.willpeavy.com/minifier/) (1st result in [Google search for "html minifier"](https://www.google.com/#q=html+minifier)) as well as [htmlcompressor.com](http://htmlcompressor.com) and [minimize](https://github.com/Swaagie/minimize)? | Site | Original size *(KB)* | HTMLMinifier | minimize | Will Peavy | htmlcompressor.com | | --------------------------------------------------------------------------- |:--------------------:| ------------:| --------:| ----------:| ------------------:| | [Google](https://www.google.com/) | 45 | **42** | 45 | 46 | 45 | | [HTMLMinifier](https://github.com/kangax/html-minifier) | 131 | **102** | 110 | 114 | 109 | | [CNN](http://www.cnn.com/) | 134 | **122** | 131 | 132 | 126 | | [Amazon](http://www.amazon.co.uk/) | 201 | **169** | 193 | 197 | n/a | | [New York Times](http://www.nytimes.com/) | 216 | **144** | 165 | 161 | 151 | | [Stack Overflow](http://stackoverflow.com/) | 240 | **187** | 196 | 203 | 193 | | [Bootstrap CSS](http://getbootstrap.com/css/) | 272 | **260** | 269 | 229 | 269 | | [BBC](http://www.bbc.co.uk/) | 287 | **235** | 279 | 286 | 271 | | [Wikipedia](https://en.wikipedia.org/wiki/President_of_the_United_States) | 530 | **486** | 511 | 529 | 510 | | [NBC](http://www.nbc.com/) | 662 | **623** | 658 | 661 | n/a | | [Eloquent Javascript](http://eloquentjavascript.net/1st_edition/print.html) | 870 | **815** | 840 | 864 | n/a | | [ES6 table](http://kangax.github.io/compat-table/es6/) | 3844 | **3252** | 3630 | n/a | n/a | | [ES6 draft](https://tc39.github.io/ecma262/) | 5576 | **4974** | 5122 | n/a | n/a | ## Options Quick Reference Most of the options are disabled by default. | Option | Description | Default | |--------------------------------|-----------------|---------| | `caseSensitive` | Treat attributes in case sensitive manner (useful for custom HTML tags) | `false` | | `collapseBooleanAttributes` | [Omit attribute values from boolean attributes](http://perfectionkills.com/experimenting-with-html-minifier/#collapse_boolean_attributes) | `false` | | `collapseInlineTagWhitespace` | Don't leave any spaces between `display:inline;` elements when collapsing. Must be used in conjunction with `collapseWhitespace=true` | `false` | | `collapseWhitespace` | [Collapse white space that contributes to text nodes in a document tree](http://perfectionkills.com/experimenting-with-html-minifier/#collapse_whitespace) | `false` | | `conservativeCollapse` | Always collapse to 1 space (never remove it entirely). Must be used in conjunction with `collapseWhitespace=true` | `false` | | `customAttrAssign` | Arrays of regex'es that allow to support custom attribute assign expressions (e.g. `'
'`) | `[ ]` | | `customAttrCollapse` | Regex that specifies custom attribute to strip newlines from (e.g. `/ng-class/`) | | | `customAttrSurround` | Arrays of regex'es that allow to support custom attribute surround expressions (e.g. ``) | `[ ]` | | `customEventAttributes` | Arrays of regex'es that allow to support custom event attributes for `minifyJS` (e.g. `ng-click`) | `[ /^on[a-z]{3,}$/ ]` | | `decodeEntities` | Use direct Unicode characters whenever possible | `false` | | `html5` | Parse input according to HTML5 specifications | `true` | | `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. ``, `{{ ... }}`, etc.) | `[ /<%[\s\S]*?%>/, /<\?[\s\S]*?\?>/ ]` | | `includeAutoGeneratedTags` | Insert tags generated by HTML parser | `true` | | `keepClosingSlash` | Keep the trailing slash on singleton elements | `false` | | `maxLineLength` | Specify a maximum line length. Compressed output will be split by newlines at valid HTML split-points | | `minifyCSS` | Minify CSS in style elements and style attributes (uses [clean-css](https://github.com/jakubpawlowicz/clean-css)) | `false` (could be `true`, `Object`, `Function(text)`) | | `minifyJS` | Minify JavaScript in script elements and event attributes (uses [UglifyJS](https://github.com/mishoo/UglifyJS2)) | `false` (could be `true`, `Object`, `Function(text, inline)`) | | `minifyURLs` | Minify URLs in various attributes (uses [relateurl](https://github.com/stevenvachon/relateurl)) | `false` (could be `String`, `Object`, `Function(text)`) | | `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` | | `preventAttributesEscaping` | Prevents the escaping of the values of attributes | `false` | | `processConditionalComments` | Process contents of conditional comments through minifier | `false` | | `processScripts` | Array of strings corresponding to types of script elements to process through minifier (e.g. `text/ng-template`, `text/x-handlebars-template`, etc.) | `[ ]` | | `quoteCharacter` | Type of quote to use for attribute values (' or ") | | | `removeAttributeQuotes` | [Remove quotes around attributes when possible](http://perfectionkills.com/experimenting-with-html-minifier/#remove_attribute_quotes) | `false` | | `removeComments` | [Strip HTML comments](http://perfectionkills.com/experimenting-with-html-minifier/#remove_comments) | `false` | | `removeEmptyAttributes` | [Remove all attributes with whitespace-only values](http://perfectionkills.com/experimenting-with-html-minifier/#remove_empty_or_blank_attributes) | `false` (could be `true`, `Function(attrName, tag)`) | | `removeEmptyElements` | [Remove all elements with empty contents](http://perfectionkills.com/experimenting-with-html-minifier/#remove_empty_elements) | `false` | | `removeOptionalTags` | [Remove optional tags](http://perfectionkills.com/experimenting-with-html-minifier/#remove_optional_tags) | `false` | | `removeRedundantAttributes` | [Remove attributes when value matches default.](http://perfectionkills.com/experimenting-with-html-minifier/#remove_redundant_attributes) | `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` | | `removeTagWhitespace` | Remove space between attributes whenever possible. **Note that this will result in invalid HTML!** | `false` | | `sortAttributes` | [Sort attributes by frequency](#sorting-attributes--style-classes) | `false` | | `sortClassName` | [Sort style classes by frequency](#sorting-attributes--style-classes) | `false` | | `trimCustomFragments` | Trim white space around `ignoreCustomFragments`. | `false` | | `useShortDoctype` | [Replaces the `doctype` with the short (HTML5) doctype](http://perfectionkills.com/experimenting-with-html-minifier/#use_short_doctype) | `false` | ### Sorting attributes / style classes Minifier options like `sortAttributes` and `sortClassName` won't impact the plain-text size of the output. However, they form long repetitive chains of characters that should improve compression ratio of gzip used in HTTP compression. ## Special cases ### Ignoring chunks of markup If you have chunks of markup you would like preserved, you can wrap them ``. ### Preserving SVG tags 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. ### Working with invalid markup 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 ignored, etc.), then it creates a markup out of that tree and returns it. Input markup (e.g. `

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. `

foo

`) 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. ## Installation Instructions From NPM for use as a command line app: ```shell npm install html-minifier -g ``` From NPM for programmatic use: ```shell npm install html-minifier ``` From Git: ```shell git clone git://github.com/kangax/html-minifier.git cd html-minifier npm link . ``` ## Usage For command line usage please see `html-minifier --help` ### Node.js ```js var minify = require('html-minifier').minify; var result = minify('

foo

', { removeAttributeQuotes: true }); result; // '

foo

' ``` ## Running benchmarks Benchmarks for minified HTML: ```shell node benchmark.js ```