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html-loader

Exports HTML as string. HTML is minimized when the compiler demands.

Getting Started

To begin, you'll need to install html-loader:

npm install --save-dev html-loader

Then add the plugin to your webpack config. For example:

file.js

import html from './file.html';

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.html$/i,
        loader: 'html-loader',
      },
    ],
  },
};

Options

Name	Type	Default	Description
`attributes`	`{Boolean\|Object}`	`true`	Enables/Disables attributes handling
`preprocessor`	`{Function}`	`undefined`	Allows pre-processing of content before handling
`minimize`	`{Boolean\|Object}`	`true` in production mode, otherwise `false`	Tell `html-loader` to minimize HTML
`esModule`	`{Boolean}`	`false`	Use ES modules syntax

`attributes`

Type: Boolean|Object Default: true

By default every loadable attributes (for example - <img src="image.png">) is imported (const img = require('./image.png') or import img from "./image.png""). You may need to specify loaders for images in your configuration (recommended file-loader or url-loader).

Supported tags and attributes:

the src attribute of the audio tag
the src attribute of the embed tag
the src attribute of the img tag
the srcset attribute of the img tag
the src attribute of the input tag
the data attribute of the object tag
the src attribute of the script tag
the href attribute of the script tag
the xlink:href attribute of the script tag
the src attribute of the source tag
the srcset attribute of the source tag
the src attribute of the track tag
the poster attribute of the video tag
the src attribute of the video tag
the xlink:href attribute of the image tag
the href attribute of the image tag
the xlink:href attribute of the use tag
the href attribute of the use tag
the href attribute of the link tag when the rel attribute contains stylesheet, icon, shortcut icon, mask-icon, apple-touch-icon, apple-touch-icon-precomposed, apple-touch-startup-image
the content attribute of the meta tag when the name attribute is msapplication-tileimage, msapplication-square70x70logo, msapplication-square150x150logo, msapplication-wide310x150logo, msapplication-square310x310logo, msapplication-config or when the property attribute is og:image, og:image:url, og:image:secure_url, og:audio, og:audio:secure_url, og:video, og:video:secure_url, vk:image

`Boolean`

The true value enables processing of all default elements and attributes, the false disable processing of all attributes.

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.html$/i,
        loader: 'html-loader',
        options: {
          // Disables attributes processing
          attributes: false,
        },
      },
    ],
  },
};

`Object`

Allows you to specify which tags and attributes to process, filter them, filter urls and process sources starts with /.

For example:

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.html$/i,
        loader: 'html-loader',
        options: {
          attributes: {
            list: [
              // All default supported tags and attributes
              '...',
              {
                tag: 'img',
                attribute: 'data-src',
                type: 'src',
              },
              {
                tag: 'img',
                attribute: 'data-srcset',
                type: 'srcset',
              },
            ],
            urlFilter: (attribute, value, resourcePath) => {
              // The `attribute` argument contains a name of the HTML attribute.
              // The `value` argument contains a value of the HTML attribute.
              // The `resourcePath` argument contains a path to the loaded HTML file.

              if (/example\.pdf$/.test(value)) {
                return false;
              }

              return true;
            },
            root: '.',
          },
        },
      },
    ],
  },
};

`list`

Type: Array Default: supported tags and attributes.

Allows to setup which tags and attributes to process and how, and the ability to filter some of them.

Using ... syntax allows you to extend default supported tags and attributes.

For example:

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.html$/i,
        loader: 'html-loader',
        options: {
          attributes: {
            list: [
              // All default supported tags and attributes
              '...',
              {
                tag: 'img',
                attribute: 'data-src',
                type: 'src',
              },
              {
                tag: 'img',
                attribute: 'data-srcset',
                type: 'srcset',
              },
              {
                // Tag name
                tag: 'link',
                // Attribute name
                attribute: 'href',
                // Type of processing, can be `src` or `scrset`
                type: 'src',
                // Allow to filter some attributes
                filter: (tag, attribute, attributes, resourcePath) => {
                  // The `tag` argument contains a name of the HTML tag.
                  // The `attribute` argument contains a name of the HTML attribute.
                  // The `attributes` argument contains all attributes of the tag.
                  // The `resourcePath` argument contains a path to the loaded HTML file.

                  if (/my-html\.html$/.test(resourcePath)) {
                    return false;
                  }

                  if (!/stylesheet/i.test(attributes.rel)) {
                    return false;
                  }

                  if (
                    attributes.type &&
                    attributes.type.trim().toLowerCase() !== 'text/css'
                  ) {
                    return false;
                  }

                  return true;
                },
              },
            ],
          },
        },
      },
    ],
  },
};

If the tag name is not specified it will process all the tags.

You can use your custom filter to specify html elements to be processed.

For example:

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.html$/i,
        loader: 'html-loader',
        options: {
          attributes: {
            list: [
              {
                // Attribute name
                attribute: 'src',
                // Type of processing, can be `src` or `scrset`
                type: 'src',
                // Allow to filter some attributes (optional)
                filter: (tag, attribute, attributes, resourcePath) => {
                  // The `tag` argument contains a name of the HTML tag.
                  // The `attribute` argument contains a name of the HTML attribute.
                  // The `attributes` argument contains all attributes of the tag.
                  // The `resourcePath` argument contains a path to the loaded HTML file.

                  // choose all HTML tags except img tag
                  return tag.toLowerCase() !== 'img';
                },
              },
            ],
          },
        },
      },
    ],
  },
};

`urlFilter`

Type: Function Default: undefined

Allow to filter urls. All filtered urls will not be resolved (left in the code as they were written). All non requestable sources (for example <img src="javascript:void(0)">) do not handle by default.

module.exports = {
  module: {
    rules: [
      {
        test: /\.html$/i,
        loader: 'html-loader',
        options: {
          attributes: {
            urlFilter: (attribute, value, resourcePath) => {
              // The `attribute` argument contains a name of the HTML attribute.
              // The `value` argument contains a value of the HTML attribute.
              // The `resourcePath` argument contains a path to the loaded HTML file.

              if (/example\.pdf$/.test(value)) {
                return false;
              }

              return true;
            },
          },
        },
      },
    ],
  },
};

`root`

Type: String Default: undefined

For urls that start with a /, the default behavior is to not translate them. If a root query parameter is set, however, it will be prepended to the url and then translated.

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.html$/i,
        loader: 'html-loader',
        options: {
          attributes: {
            root: '.',
          },
        },
      },
    ],
  },
};

`preprocessor`

Type: Function Default: undefined

Allows pre-processing of content before handling.

⚠ You should always return valid HTML

file.hbs

<div>
  <p>{{firstname}} {{lastname}}</p>
  <img src="image.png" alt="alt" />
<div>

`Function`

You can set the preprocessor option as a Function instance.

webpack.config.js

const Handlebars = require('handlebars');

module.exports = {
  module: {
    rules: [
      {
        test: /\.hbs$/i,
        loader: 'html-loader',
        options: {
          preprocessor: (content, loaderContext) => {
            let result;

            try {
              result = Handlebars.compile(content)({
                firstname: 'Value',
                lastname: 'OtherValue',
              });
            } catch (error) {
              loaderContext.emitError(error);

              return content;
            }

            return result;
          },
        },
      },
    ],
  },
};

You can also set the preprocessor option as an asynchronous function instance.

For example:

webpack.config.js

const Handlebars = require('handlebars');

module.exports = {
  module: {
    rules: [
      {
        test: /\.hbs$/i,
        loader: 'html-loader',
        options: {
          preprocessor: async (content, loaderContext) => {
            let result;

            try {
              result = await Handlebars.compile(content)({
                firstname: 'Value',
                lastname: 'OtherValue',
              });
            } catch (error) {
              await loaderContext.emitError(error);

              return content;
            }

            return result;
          },
        },
      },
    ],
  },
};

`minimize`

Type: Boolean|Object Default: true in production mode, otherwise false

Tell html-loader to minimize HTML.

`Boolean`

The enabled rules for minimizing by default are the following ones:

({
  caseSensitive: true,
  collapseWhitespace: true,
  conservativeCollapse: true,
  keepClosingSlash: true,
  minifyCSS: true,
  minifyJS: true,
  removeComments: true,
  removeRedundantAttributes: true,
  removeScriptTypeAttributes: true,
  removeStyleLinkTypeAttributes: true,
});

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.html$/i,
        loader: 'html-loader',
        options: {
          minimize: true,
        },
      },
    ],
  },
};

`Object`

webpack.config.js

See html-minifier-terser's documentation for more information on the available options.

The rules can be disabled using the following options in your webpack.conf.js

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.html$/i,
        loader: 'html-loader',
        options: {
          minimize: {
            removeComments: false,
            collapseWhitespace: false,
          },
        },
      },
    ],
  },
};

`esModule`

Type: Boolean Default: false

By default, html-loader generates JS modules that use the CommonJS modules syntax. There are some cases in which using ES modules is beneficial, like in the case of module concatenation and tree shaking.

You can enable a ES module syntax using:

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.html$/i,
        loader: 'html-loader',
        options: {
          esModule: true,
        },
      },
    ],
  },
};

Examples

CDN

webpack.config.js

module.exports = {
  module: {
    rules: [
      { test: /\.jpg$/, loader: 'file-loader' },
      { test: /\.png$/, loader: 'url-loader' },
    ],
  },
  output: {
    publicPath: 'http://cdn.example.com/[hash]/',
  },
};

file.html

<img src="image.jpg" data-src="image2x.png" />

index.js

require('html-loader!./file.html');

// => '<img src="http://cdn.example.com/49eba9f/a992ca.jpg" data-src="image2x.png">'

require('html-loader?{"attributes":{"list":[{"tag":"img","attribute":"data-src","type":"src"}]}}!./file.html');

// => '<img src="image.jpg" data-src="data:image/png;base64,..." >'

require('html-loader?{"attributes":{"list":[{"tag":"img","attribute":"src","type":"src"},{"tag":"img","attribute":"data-src","type":"src"}]}}!./file.html');

// => '<img src="http://cdn.example.com/49eba9f/a992ca.jpg" data-src="data:image/png;base64,..." >'

require('html-loader?-attributes!./file.html');

// => '<img src="image.jpg"  data-src="image2x.png" >'

:warning: -attributes sets attributes: false.

Process `script` and `link` tags

script.file.js

console.log(document);

style.file.css

a {
  color: red;
}

file.html

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8" />
    <title>Title of the document</title>
    <link rel="stylesheet" type="text/css" href="./style.file.css" />
  </head>
  <body>
    Content of the document......
    <script src="./script.file.js"></script>
  </body>
</html>

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.html$/i,
        use: ['file-loader?name=[name].[ext]', 'extract-loader', 'html-loader'],
      },
      {
        test: /\.js$/i,
        exclude: /\.file.js$/i,
        loader: 'babel-loader',
      },
      {
        test: /\.file.js$/i,
        loader: 'file-loader',
      },
      {
        test: /\.css$/i,
        exclude: /\.file.css$/i,
        loader: 'css-loader',
      },
      {
        test: /\.file.css$/i,
        loader: 'file-loader',
      },
    ],
  },
};

'Root-relative' URLs

With the same configuration as in the CDN example:

file.html

<img src="/image.jpg" />

scripts.js

require('html-loader!./file.html');

// => '<img src="/image.jpg">'

other-scripts.js

require('html-loader?{"attributes":{"root":"."}}!./file.html');

// => '<img src="http://cdn.example.com/49eba9f/a992ca.jpg">'

Templating

You can use any template system. Below is an example for handlebars.

file.hbs

<div>
  <p>{{firstname}} {{lastname}}</p>
  <img src="image.png" alt="alt" />
<div>

webpack.config.js

const Handlebars = require('handlebars');

module.exports = {
  module: {
    rules: [
      {
        test: /\.hbs$/i,
        loader: 'html-loader',
        options: {
          preprocessor: (content, loaderContext) => {
            let result;

            try {
              result = Handlebars.compile(content)({
                firstname: 'Value',
                lastname: 'OtherValue',
              });
            } catch (error) {
              loaderContext.emitError(error);

              return content;
            }

            return result;
          },
        },
      },
    ],
  },
};

PostHTML

You can use PostHTML without any additional loaders.

file.html

<img src="image.jpg" />

webpack.config.js

const posthtml = require('posthtml');
const posthtmlWebp = require('posthtml-webp');

module.exports = {
  module: {
    rules: [
      {
        test: /\.hbs$/i,
        loader: 'html-loader',
        options: {
          preprocessor: (content, loaderContext) => {
            let result;

            try {
              result = posthtml().use(plugin).process(content, { sync: true });
            } catch (error) {
              loaderContext.emitError(error);

              return content;
            }

            return result.html;
          },
        },
      },
    ],
  },
};

Export into HTML files

A very common scenario is exporting the HTML into their own .html file, to serve them directly instead of injecting with javascript. This can be achieved with a combination of 3 loaders:

The html-loader will parse the URLs, require the images and everything you expect. The extract loader will parse the javascript back into a proper html file, ensuring images are required and point to proper path, and the file loader will write the .html file for you. Example:

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.html$/i,
        use: ['file-loader?name=[name].[ext]', 'extract-loader', 'html-loader'],
      },
    ],
  },
};

Contributing

Please take a moment to read our contributing guidelines if you haven't yet done so.

CONTRIBUTING

License

MIT

« Previous

file-loader

imports-loader

html-loader

Getting Started

Options

attributes

Boolean

Object

list

urlFilter

root

preprocessor

Function

minimize

Boolean

Object

esModule

Examples

CDN

Process script and link tags

'Root-relative' URLs

Templating

PostHTML

Export into HTML files

Contributing

License

`attributes`

`Boolean`

`Object`

`list`

`urlFilter`

`root`

`preprocessor`

`Function`

`minimize`

`Boolean`

`Object`

`esModule`

Process `script` and `link` tags