htmlnano

Modular HTML minifier, built on top of the PostHTML. Inspired by cssnano.

Benchmark

Usage

Gulp

npm install --save-dev gulp-htmlnano

var gulp = require('gulp');
var htmlnano = require('gulp-htmlnano');
var options = {
    removeComments: false
};

gulp.task('default', function() {
    return gulp
        .src('./index.html')
        .pipe(htmlnano(options))
        .pipe(gulp.dest('./build'));
});

Javascript

var htmlnano = require('htmlnano');
var options = {
    removeEmptyAttributes: false, // Disable the module "removeEmptyAttributes"
    collapseWhitespace: 'conservative' // Pass options to the module "collapseWhitespace"
};

htmlnano
    .process(html, options)
    .then(function (result) {
        // result.html is minified
    })
    .catch(function (err) {
        console.error(err);
    });

PostHTML

Just add htmlnano as the last plugin:

var posthtml = require('posthtml');
var options = {
    removeComments: false, // Disable the module "removeComments"
    collapseWhitespace: 'conservative' // Pass options to the module "collapseWhitespace"
};
var posthtmlPlugins = [
    /* other PostHTML plugins */

    require('htmlnano')(options)
];

posthtml(posthtmlPlugins)
    .process(html)
    .then(function (result) {
        // result.html is minified
    })
    .catch(function (err) {
        console.error(err);
    });

// You can also use htmlnano modules separately:
posthtml([
    require('htmlnano/lib/modules/mergeStyles').default
]).process(html);

Modules

By default the modules should only perform safe transforms, see the module documentation below for details. You can disable modules by passing false as option, and enable them by passing true.

collapseWhitespace

Collapses redundant white spaces (including new lines). It doesn’t affect white spaces in the elements <style>, <textarea>, <script> and <pre>.

Options

• conservative — collapses all redundant white spaces to 1 space (default)
• all — collapses all redundant white spaces

Side effects

<i>hello</i> <i>world</i> after minification will be rendered as helloworld. To prevent that use conservative option (this is the default option).

Example

Source:

<div>
    hello  world!
    <style>div  { color: red; }  </style>
</div>

Minified (with all):

<div>hello world!<style>div  { color: red; }  </style></div>

Minified (with conservative):

<div> hello world! <style>div  { color: red; }  </style> </div>

removeComments

Options

• safe – removes all HTML comments except the conditional comments and <!--noindex--><!--/noindex--> (default)
• all — removes all HTML comments

Example

Source:

<div><!-- test --></div>

Minified:

<div></div>

removeEmptyAttributes

Removes empty safe-to-remove attributes.

Side effects

This module could break your styles or JS if you use selectors with attributes:

img[style=""] {
    margin: 10px;
}

Example

Source:

<img src="foo.jpg" alt="" style="">

Minified:

<img src="foo.jpg" alt="">

minifyCss

Minifies CSS with cssnano inside <style> tags and style attributes.

Options

Css transforms are set to the safe option as a default (this should have very little side-effects):

"minifyCss": {
    "safe": true
}

See the documentation of cssnano. For example you can keep outdated vendor prefixes:

htmlnano.process(html, {
    minifyCss: {
        autoprefixer: false
    }
});

Example

Source:

<div>
    <style>
        h1 {
            margin: 10px 10px 10px 10px;
            color: #ff0000;
        }
    </style>
</div>

Minified:

<div>
    <style>h1{margin:10px;color:red}</style>
</div>

minifyJs

Minifies JS with Terser inside <script> tags.

Options

See the API documentation of Terser

Example

Source:

<div>
    <script>
        /* comment */
        var foo = function () {

        };
    </script>
</div>

Minified:

<div>
    <script>var foo=function(){};</script>
</div>

minifyJson

Minifies JSON inside <script type="application/json"></script>.

Example

Source:

<script type="application/json">
{
    "user": "me"
}
</script>

Minified:

<script type="application/json">{"user":"me"}</script>

minifySvg

Minifies SVG inside <svg> tags with SVGO.

Options

See the documentation of SVGO

Example

Source:

<svg version="1.1" baseProfile="full" width="300" height="200" xmlns="http://www.w3.org/2000/svg">
    <rect width="100%" height="100%" fill="red" />

    <circle cx="150" cy="100" r="80" fill="green" />

    <text x="150" y="125" font-size="60" text-anchor="middle" fill="white">SVG</text>
</svg>`

Minified:

<svg baseProfile="full" width="300" height="200" xmlns="http://www.w3.org/2000/svg"><rect width="100%" height="100%" fill="red"/><circle cx="150" cy="100" r="80" fill="green"/><text x="150" y="125" font-size="60" text-anchor="middle" fill="#fff">SVG</text></svg>

removeRedundantAttributes

Removes redundant attributes from tags if they contain default values:

• method="get" from <form>
• type="text" from <input>
• type="submit" from <button>
• language="javascript" and type="text/javascript" from <script>
• charset from <script> if it's an external script
• media="all" from <style> and <link>

Options

This module is disabled by default, change option to true to enable this module.

Side effects

This module could break your styles or JS if you use selectors with attributes:

form[method="get"] {
    color: red;
}

Example

Source:

<form method="get">
    <input type="text">
</form>

Minified:

<form>
    <input>
</form>

collapseBooleanAttributes

Collapses boolean attributes (like disabled) to the minimized form.

Side effects

This module could break your styles or JS if you use selectors with attributes:

button[disabled="disabled"] {
    color: red;
}

Example

Source:

<button disabled="disabled">click</button>
<script defer=""></script>

Minified:

<button disabled>click</button>
<script defer></script>

mergeStyles

Merges multiple <style> with the same media and type into one tag. <style scoped>...</style> are skipped.

Example

Source:

<style>h1 { color: red }</style>
<style media="print">div { color: blue }</style>

<style type="text/css" media="print">a {}</style>
<style>div { font-size: 20px }</style>

Minified:

<style>h1 { color: red } div { font-size: 20px }</style>
<style media="print">div { color: blue } a {}</style>

mergeScripts

Merge multiple <script> with the same attributes (id, class, type, async, defer) into one (last) tag.

Side effects

It could break your code if the tags with different attributes share the same variable scope. See the example below.

Example

Source:

<script>var foo = 'A:1';</script>
<script class="test">foo = 'B:1';</script>
<script type="text/javascript">foo = 'A:2';</script>
<script defer>foo = 'C:1';</script>
<script>foo = 'A:3';</script>
<script defer="defer">foo = 'C:2';</script>
<script class="test" type="text/javascript">foo = 'B:2';</script>

Minified:

<script>var foo = 'A:1'; foo = 'A:2'; foo = 'A:3';</script>
<script defer="defer">foo = 'C:1'; foo = 'C:2';</script>
<script class="test" type="text/javascript">foo = 'B:1'; foo = 'B:2';</script>

custom

It's also possible to pass custom modules in the minifier.

As a function:

var options = {
    custom: function (tree, options) {
        // Some minification
        return tree;
    }
};

Or as a list of functions:

var options = {
    custom: [
        function (tree, options) {
            // Some minification
            return tree;
        },

        function (tree, options) {
            // Some other minification
            return tree;
        }
    ]
};

options is an object with all options that were passed to the plugin.

Contribute

Since the minifier is modular, it's very easy to add new modules:

1. Create a ES6-file inside lib/modules/ with a function that does some minification. For example you can check lib/modules/example.es6.

2. Add the module in the modules array. The modules are applied from top to bottom. So you can choose the order for your module.

3. Create a JS-file inside test/modules/ with some unit-tests.

4. Describe your module in the section "Modules".

5. Send me a pull request.

Other types of contribution (bug fixes, documentation improves, etc) are also welcome! Would like to contribute, but don't have any ideas what to do? Check out our issues.