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Version: 2.0.0

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.

collapseAttributeWhitespace​

Collapse redundant white spaces in list-like attributes (class, rel, ping).

Example​

Source:

<a class=" content  page  " style="  display: block;    " href="   https://example.com"></a>

Minified:

<a class="content page" style="display: block;" href="https://example.com"></a>

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)
  • aggressive — collapses all whitespaces that are redundant and safe to remove
  • all — collapses all redundant white spaces

Side effects​

all <i>hello</i> <i>world</i> or <i>hello</i><br><i>world</i> after minification will be rendered as helloworld. To prevent that use either the default conservative option, or the aggressive option.

Example​

Source:

<div>
    hello  world!
    <a href="#">answer</a>
    <style>div  { color: red; }  </style>
    <main></main>
</div>

Minified (with all):

<div>hello world!<a href="#">answer</a><style>div  { color: red; }  </style><main></main></div>

Minified (with aggressive):

<div> hello world! <a href="#">answer</a> <style>div  { color: red; }  </style><main></main></div>

Minified (with conservative):

<div> hello world! <a href="#">answer</a> <style>div  { color: red; }  </style> <main></main> </div>

deduplicateAttributeValues​

Remove duplicate values from list-like attributes (class, rel, ping).

Example​

Source:

<div class="sidebar left sidebar"></div>

Minified:

<div class="sidebar left"></div>

removeComments​

Options​

  • safe – removes all HTML comments except the conditional comments and <!--noindex--><!--/noindex--> (default)
  • all — removes all HTML comments
  • A RegExp — only HTML comments matching the given regexp will be removed.
  • A Function that returns boolean — removes HTML comments that can make the given callback function returns truthy value.

Example​

Source:

{
    removeComments: 'all'
}
<div><!-- test --></div>

Minified:

<div></div>

Source:

{
    removeComments: /<!--(\/)?noindex-->/
}
<div><!--noindex-->this text will not be indexed<!--/noindex-->Lorem ipsum dolor sit amet<!--more-->Lorem ipsum dolor sit amet</div>

Minified:

<div>this text will not be indexedLorem ipsum dolor sit amet<!--more-->Lorem ipsum dolor sit amet</div>

Source:

{
    removeComments: (comments) => {
        if (comments.includes('noindex')) return true;
        return false;
    }
}
<div><!--noindex-->this text will not be indexed<!--/noindex-->Lorem ipsum dolor sit amet<!--more-->Lorem ipsum dolor sit amet</div>

Minified:

<div>this text will not be indexedLorem ipsum dolor sit amet<!--more-->Lorem ipsum dolor sit amet</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="">

removeAttributeQuotes​

Remove quotes around attributes when possible, see HTML Standard - 12.1.2.3 Attributes - Unquoted attribute value syntax.

Example​

Source:

<div class="foo" title="hello world"></div>

Minified:

<div class=foo title="hello world"></div>

Notice​

The feature is implemented by posthtml-render's quoteAllAttributes, which is one of the PostHTML's option. So removeAttributeQuotes could be overriden by other PostHTML's plugins and PostHTML's configuration.

For example:

posthtml([
    htmlnano({
        removeAttributeQuotes: true
    })
]).process(html, {
    quoteAllAttributes: true
})

removeAttributeQuotes will not work because PostHTML's quoteAllAttributes takes the priority.

removeUnusedCss​

Removes unused CSS inside <style> tags with either uncss or PurgeCSS.

With uncss​

You have to install uncss in order to use this feature:

npm install --save-dev uncss
# if you prefer yarn
# yarn add --dev uncss
# if you prefer pnpm
# pnpm install --save-dev uncss

You can also use a mainted fork @novaatwarren/uncss instead.

Options​

See the documentation of uncss for all supported options.

uncss options can be passed directly to the removeUnusedCss module:

htmlnano.process(html, {
    removeUnusedCss: {
        ignore: ['.do-not-remove']
    }
});

The following uncss options are ignored if passed to the module:

  • stylesheets
  • ignoreSheets
  • raw

With PurgeCSS​

Use PurgeCSS instead of uncss by adding tool: 'purgeCSS' to the options.

You have to install purgecss in order to use this feature:

npm install --save-dev purgecss
# if you prefer yarn
# yarn add --dev purgecss
# if you prefer pnpm
# pnpm install --save-dev purgecss
Options​

See the documentation of PurgeCSS for all supported options.

PurgeCSS options can be passed directly to the removeUnusedCss module:

htmlnano.process(html, {
    removeUnusedCss: {
        tool: 'purgeCSS',
        safelist: ['.do-not-remove']
    }
});

The following PurgeCSS options are ignored if passed to the module:

  • content
  • css
  • extractors

Example​

Source:

<div class="b">
    <style>
        .a {
            margin: 10px 10px 10px 10px;
        }
        .b {
            color: #ff0000;
        }
    </style>
</div>

Optimized:

<div class="b">
    <style>
        .b {
            color: #ff0000;
        }
    </style>
</div>

minifyCss​

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

You have to install cssnano and postcss in order to use this feature:

npm install --save-dev cssnano postcss
# if you prefer yarn
# yarn add --dev cssnano postcss
# if you prefer pnpm
# pnpm install --save-dev cssnano postcss

Options​

See the documentation of cssnano for all supported optimizations. By default CSS is minified with preset default, which shouldn't have any side-effects.

To use another preset or disabled some optimizations pass options to minifyCss module:

htmlnano.process(html, {
    minifyCss: {
        preset: ['default', {
            discardComments: {
                removeAll: true,
            },
        }]
    }
});

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 using Terser inside <script> tags.

You have to install terser in order to use this feature:

npm install --save-dev terser
# if you prefer yarn
# yarn add --dev terser
# if you prefer pnpm
# pnpm install --save-dev terser

Options​

See the documentation of Terser for all supported options. Terser options can be passed directly to the minifyJs module:

htmlnano.process(html, {
    minifyJs: {
        output: { quote_style: 1 },
    },
});

Example​

Source:

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

        };
    </script>
</div>

Minified:

<div>
    <script>const 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 using SVGO.

Options​

See the documentation of SVGO for all supported options. SVGO options can be passed directly to the minifySvg module:

htmlnano.process(html, {
    minifySvg: {
        plugins: [
            {
                name: 'preset-default',
                params: {
                    overrides: {
                        builtinPluginName: {
                            optionName: 'optionValue'
                        },
                    },
                },
            }
        ]
    }
});

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>

minifyConditionalComments​

Minify content inside conditional comments.

Example​

Source:

<!--[if lte IE 7]>
<style type="text/css">
.title {
  color: red;
}
</style>
<![endif]-->

Minified:

<!--[if lte IE 7]><style>.title{color:red}</style><![endif]-->

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>
  • type="text/css" from <link rel="stylesheet">

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.

Options​

If your document uses AMP, set the amphtml flag to collapse additonal, AMP-specific boolean attributes:

"collapseBooleanAttributes": {
    "amphtml": true
}

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>const 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>const 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:

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

Or as a list of functions:

const 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.

sortAttributesWithLists​

Sort values in list-like attributes (class, rel, ping).

The module won't impact the plain-text size of the output. However it will improve the compression ratio of gzip/brotli used in HTTP compression.

Options​

  • alphabetical: Default option. Sort attribute values in alphabetical order.
  • frequency: Sort attribute values by frequency.

Example​

alphabetical

Source:

<div class="foo baz bar">click</div>

Processed:

<div class="bar baz foo">click</div>

frequency

Source:

<div class="foo baz bar"></div><div class="bar foo"></div>

Processed:

<div class="foo bar baz"></div><div class="foo bar"></div>

sortAttributes​

Sort attributes inside elements.

The module won't impact the plain-text size of the output. However it will improve the compression ratio of gzip/brotli used in HTTP compression.

Options​

  • alphabetical: Default option. Sort attributes in alphabetical order.
  • frequency: Sort attributes by frequency.

Example​

alphabetical

Source:

<input type="text" class="form-control" name="testInput" autofocus="" autocomplete="off" id="testId">

Processed:

<input autocomplete="off" autofocus="" class="form-control" id="testId" name="testInput" type="text">

frequency

Source:

<input type="text" class="form-control" name="testInput" id="testId">
<a id="testId" href="#" class="testClass"></a>
<img width="20" src="../images/image.png" height="40" alt="image" class="cls" id="id2">

Processed:

<input class="form-control" id="testId" type="text" name="testInput">
<a class="testClass" id="testId" href="#"></a>
<img class="cls" id="id2" width="20" src="../images/image.png" height="40" alt="image">

minifyUrls​

Convert absolute URL to relative URL using relateurl.

You have to install relateurl, terser and srcset in order to use this feature:

npm install --save-dev relateurl terser srcset
# if you prefer yarn
# yarn add --dev relateurl terser srcset
# if you prefer pnpm
# pnpm install --save-dev relateurl terser srcset

Options​

The base URL to resolve against. Support String & URL.

htmlnano.process(html, {
    minifyUrls: 'https://example.com' // Valid configuration
});
htmlnano.process(html, {
    minifyUrls: new URL('https://example.com') // Valid configuration
});
htmlnano.process(html, {
    minifyUrls: false // The module will be disabled
});
htmlnano.process(html, {
    minifyUrls: true // Invalid configuration, the module will be disabled
});

Example​

Basic Usage

Configuration:

htmlnano.process(html, {
    minifyUrls: 'https://example.com'
});

Source:

<a href="https://example.com/foo/bar/baz">bar</a>

Minified:

<a href="foo/bar/baz">bar</a>

With sub-directory

Configuration:

htmlnano.process(html, {
    minifyUrls: 'https://example.com/foo/baz/'
});

Source:

<a href="https://example.com/foo/bar">bar</a>

Minified:

<a href="../bar">bar</a>

removeOptionalTags​

Remove certain tags that can be omitted, see HTML Standard - 13.1.2.4 Optional tags.

Example​

Source:

<html><head><title>Title</title></head><body><p>Hi</p></body></html>

Minified:

<title>Title</title><p>Hi</p>

Notice​

Due to the limitation of PostHTML, htmlnano can't remove only the start tag or the end tag of an element. Currently, htmlnano only supports removing the following optional tags, as htmlnano can remove their start tag and end tag at the same time:

  • html
  • head
  • body
  • colgroup
  • tbody

normalizeAttributeValues​

Normalize casing of attribute values.

The module won't impact the plain-text size of the output. However it will improve the compression ratio of gzip/brotli used in HTTP compression.

Example​

Source:

<form method="GET"></form>

Minified:

<form method="get"></form>