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html-minifier v3.5.1

Highly configurable, well-tested, JavaScript-based HTML minifier.

HTMLMinifier

NPM version Build Status Dependency Status devDependency Status Gitter

HTMLMinifier is a highly configurable, well-tested, JavaScript-based HTML minifier.

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, Koa middleware wrapper and Express middleware wrapper.

For lint-like capabilities take a look at HTMLLint.

Minification comparison

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?

SiteOriginal size (KB)HTMLMinifierminimizeWill Peavyhtmlcompressor.com
Google4442454645
HTMLMinifier127100108112107
CNN136125133134129
Amazon196165188192n/a
Stack Overflow223172181188178
New York Times224153172170159
BBC236194229236223
Bootstrap CSS272260269229269
Wikipedia550503530548529
NBC643612641643n/a
Eloquent Javascript870815840864n/a
ES6 table410534673871n/an/a
ES6 draft551249195066n/an/a

Options Quick Reference

Most of the options are disabled by default.

OptionDescriptionDefault
caseSensitiveTreat attributes in case sensitive manner (useful for custom HTML tags)false
collapseBooleanAttributesOmit attribute values from boolean attributesfalse
collapseInlineTagWhitespaceDon't leave any spaces between display:inline; elements when collapsing. Must be used in conjunction with collapseWhitespace=truefalse
collapseWhitespaceCollapse white space that contributes to text nodes in a document treefalse
conservativeCollapseAlways collapse to 1 space (never remove it entirely). Must be used in conjunction with collapseWhitespace=truefalse
customAttrAssignArrays of regex'es that allow to support custom attribute assign expressions (e.g. '<div flex?="{{mode != cover}}"></div>')[ ]
customAttrCollapseRegex that specifies custom attribute to strip newlines from (e.g. /ng-class/)
customAttrSurroundArrays of regex'es that allow to support custom attribute surround expressions (e.g. <input {{#if value}}checked="checked"{{/if}}>)[ ]
customEventAttributesArrays of regex'es that allow to support custom event attributes for minifyJS (e.g. ng-click)[ /^on[a-z]{3,}$/ ]
decodeEntitiesUse direct Unicode characters whenever possiblefalse
html5Parse input according to HTML5 specificationstrue
ignoreCustomCommentsArray of regex'es that allow to ignore certain comments, when matched[ /^!/ ]
ignoreCustomFragmentsArray of regex'es that allow to ignore certain fragments, when matched (e.g. <?php ... ?>, {{ ... }}, etc.)[ /<%[\s\S]*?%>/, /<\?[\s\S]*?\?>/ ]
includeAutoGeneratedTagsInsert tags generated by HTML parsertrue
keepClosingSlashKeep the trailing slash on singleton elementsfalse
maxLineLengthSpecify a maximum line length. Compressed output will be split by newlines at valid HTML split-points
minifyCSSMinify CSS in style elements and style attributes (uses clean-css)false (could be true, Object, Function(text))
minifyJSMinify JavaScript in script elements and event attributes (uses UglifyJS)false (could be true, Object, Function(text, inline))
minifyURLsMinify URLs in various attributes (uses relateurl)false (could be String, Object, Function(text))
preserveLineBreaksAlways collapse to 1 line break (never remove it entirely) when whitespace between tags include a line break. Must be used in conjunction with collapseWhitespace=truefalse
preventAttributesEscapingPrevents the escaping of the values of attributesfalse
processConditionalCommentsProcess contents of conditional comments through minifierfalse
processScriptsArray of strings corresponding to types of script elements to process through minifier (e.g. text/ng-template, text/x-handlebars-template, etc.)[ ]
quoteCharacterType of quote to use for attribute values (' or ")
removeAttributeQuotesRemove quotes around attributes when possiblefalse
removeCommentsStrip HTML commentsfalse
removeEmptyAttributesRemove all attributes with whitespace-only valuesfalse (could be true, Function(attrName, tag))
removeEmptyElementsRemove all elements with empty contentsfalse
removeOptionalTagsRemove optional tagsfalse
removeRedundantAttributesRemove attributes when value matches default.false
removeScriptTypeAttributesRemove type="text/javascript" from script tags. Other type attribute values are left intactfalse
removeStyleLinkTypeAttributesRemove type="text/css" from style and link tags. Other type attribute values are left intactfalse
removeTagWhitespaceRemove space between attributes whenever possible. Note that this will result in invalid HTML!false
sortAttributesSort attributes by frequencyfalse
sortClassNameSort style classes by frequencyfalse
trimCustomFragmentsTrim white space around ignoreCustomFragments.false
useShortDoctypeReplaces the doctype with the short (HTML5) doctypefalse

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 <!-- htmlmin:ignore -->.

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. <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.

Installation Instructions

From NPM for use as a command line app:

npm install html-minifier -g

From NPM for programmatic use:

npm install html-minifier

From Git:

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

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>'

Running benchmarks

Benchmarks for minified HTML:

node benchmark.js
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