html-loader

What is html-loader?

The html-loader npm package is used to export HTML as string. When used with webpack, it allows you to require HTML files as modules. It can also minimize the HTML when the webpack 'minimize' option is enabled. It's useful for processing HTML files to include them as part of your JavaScript bundle.

What are html-loader's main functionalities?

Export HTML as String

Allows you to use HTML files as modules by exporting them as strings. This can be useful when you want to include your HTML in your JavaScript files.

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

Interpolate Custom Syntax

Enables interpolation with a custom syntax within the HTML file. This is useful for including images or other assets using a require statement.

require('html-loader?interpolate=require!./file.html')

Minimize HTML

When used with webpack, you can minimize the HTML by setting the 'minimize' option to true. This helps reduce the size of the HTML included in your JavaScript bundle.

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

Other packages similar to html-loader

raw-loader

The raw-loader package is similar to html-loader in that it allows you to import files as a string. However, it does not specifically target HTML files and does not have HTML-specific features like minimizing.

handlebars-loader

The handlebars-loader is used for compiling Handlebars templates and includes them in the webpack bundle. It's similar to html-loader but is tailored for Handlebars template syntax.

pug-loader

The pug-loader package allows you to compile Pug templates and include them in your webpack bundle. It's similar to html-loader but is designed for the Pug templating engine (formerly known as Jade).

README

HTML Loader

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

Install

npm i -D html-loader

Usage

By default every local <img src="image.png"> is required (require('./image.png')). You may need to specify loaders for images in your configuration (recommended file-loader or url-loader).

You can specify which tag-attribute combination should be processed by this loader via the query parameter attrs. Pass an array or a space-separated list of <tag>:<attribute> combinations. (Default: attrs=img:src)

If you use <custom-elements>, and lots of them make use of a custom-src attribute, you don't have to specify each combination <tag>:<attribute>: just specify an empty tag like attrs=:custom-src and it will match every element.

{
  test: /\.(html)$/,
  use: {
    loader: 'html-loader',
    options: {
      attrs: [':data-src']
    }
  }
}

To completely disable tag-attribute processing (for instance, if you're handling image loading on the client side) you can pass in attrs=false.

Examples

With this configuration:

{
  module: {
    rules: [
      { test: /\.jpg$/, use: [ "file-loader" ] },
      { test: /\.png$/, use: [ "url-loader?mimetype=image/png" ] }
    ]
  },
  output: {
    publicPath: "http://cdn.example.com/[hash]/"
  }
}

<!-- file.html -->
<img src="image.png" data-src="image2x.png" >

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

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

require("html-loader?attrs=img:data-src!./file.html");

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

require("html-loader?attrs=img:src img:data-src!./file.html");
require("html-loader?attrs[]=img:src&attrs[]=img:data-src!./file.html");

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

require("html-loader?-attrs!./file.html");

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

minimized by running webpack --optimize-minimize

'<img src=http://cdn.example.com/49eba9f/a9f92ca.jpg
      data-src=data:image/png;base64,...>'

or specify the minimize property in the rule's options in your webpack.conf.js

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

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

• removeComments
• removeCommentsFromCDATA
• removeCDATASectionsFromCDATA
• collapseWhitespace
• conservativeCollapse
• removeAttributeQuotes
• useShortDoctype
• keepClosingSlash
• minifyJS
• minifyCSS
• removeScriptTypeAttributes
• removeStyleTypeAttributes

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

module: {
  rules: [{
    test: /\.html$/,
    use: [ {
      loader: 'html-loader',
      options: {
        minimize: true,
        removeComments: false,
        collapseWhitespace: false
      }
    }],
  }]
}

'Root-relative' URLs

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.

With the same configuration as above:

<!-- file.html -->
<img src="/image.jpg">

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

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

require("html-loader?root=.!./file.html");

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

Interpolation

You can use interpolate flag to enable interpolation syntax for ES6 template strings, like so:

require("html-loader?interpolate!./file.html");

<img src="${require(`./images/gallery.png`)}">

<div>${require('./components/gallery.html')}</div>

And if you only want to use require in template and any other ${} are not to be translated, you can set interpolate flag to require, like so:

require("html-loader?interpolate=require!./file.ftl");

<#list list as list>
  <a href="${list.href!}" />${list.name}</a>
</#list>

<img src="${require(`./images/gallery.png`)}">

<div>${require('./components/gallery.html')}</div>

Export formats

There are different export formats available:

• module.exports (default, cjs format). "Hello world" becomes module.exports = "Hello world";
• exports.default (when exportAsDefault param is set, es6to5 format). "Hello world" becomes exports.default = "Hello world";
• export default (when exportAsEs6Default param is set, es6 format). "Hello world" becomes export default "Hello world";

Advanced options

If you need to pass more advanced options, especially those which cannot be stringified, you can also define an htmlLoader-property on your webpack.config.js:

var path = require('path')

module.exports = {
  ...
  module: {
    rules: [
      {
        test: /\.html$/,
        use: [ "html-loader" ]
      }
    ]
  },
  htmlLoader: {
    ignoreCustomFragments: [/\{\{.*?}}/],
    root: path.resolve(__dirname, 'assets'),
    attrs: ['img:src', 'link:href']
  }
};

If you need to define two different loader configs, you can also change the config's property name via html-loader?config=otherHtmlLoaderConfig:

module.exports = {
  ...
  module: {
    rules: [
      {
        test: /\.html$/,
        use: [ "html-loader?config=otherHtmlLoaderConfig" ]
      }
    ]
  },
  otherHtmlLoaderConfig: {
    ...
  }
};

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:

• file-loader
• extract-loader
• html-loader

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:

{
  test: /\.html$/,
  use: [ 'file-loader?name=[path][name].[ext]!extract-loader!html-loader' ]
}

Maintainers

Hemanth	Joshua Wiens	Michael Ciniawsky	Imvetri
Andrei Crnković	Yuta Hiroto	Vesselin Petrunov	Gajus Kuizinas

Changelog

0.5.0 (2017-07-26)

Features

• add support for empty tags in tag:attribute matching (#129) (70370dc)

<a name="0.4.5"></a>