html-loader
Version:
Html loader module for webpack
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Markdown
<div align="center">
<img width="200" height="200" src="https://www.w3.org/html/logo/downloads/HTML5_Logo.svg" alt="html-loader">
<a href="https://github.com/webpack/webpack">
<img width="200" height="200" vspace="" hspace="25" src="https://webpack.js.org/assets/icon-square-big.svg" alt="webpack">
</a>
</div>
[![npm][npm]][npm-url]
[![node][node]][node-url]
[![tests][tests]][tests-url]
[![coverage][cover]][cover-url]
[![discussion][discussion]][discussion-url]
[![size][size]][size-url]
# html-loader
Exports HTML as string. HTML is minimized when the compiler demands.
## Getting Started
To begin, you'll need to install `html-loader`:
```console
npm install --save-dev html-loader
```
or
```console
yarn add -D html-loader
```
or
```console
pnpm add -D html-loader
```
Then add the plugin to your `webpack` config. For example:
**file.js**
```js
import html from "./file.html";
```
**webpack.config.js**
```js
module.exports = {
module: {
rules: [
{
test: /\.html$/i,
loader: "html-loader",
},
],
},
};
```
## Options
- **[`sources`](#sources)**
- **[`preprocessor`](#preprocessor)**
- **[`postprocessor`](#postprocessor)**
- **[`minimize`](#minimize)**
- **[`esModule`](#esmodule)**
### `sources`
Type:
```ts
type sources =
| boolean
| {
list?: Array<{
tag?: string;
attribute?: string;
type?: string;
filter?: (
tag: string,
attribute: string,
attributes: string,
resourcePath: string,
) => boolean;
}>;
urlFilter?: (
attribute: string,
value: string,
resourcePath: string,
) => boolean;
scriptingEnabled?: boolean;
};
```
Default: `true`
By default every loadable attribute (for example - `<img src="image.png">`) is imported (`const img = require('./image.png')` or `new URL("./image.png", import.meta.url)`).
You may need to specify loaders for images in your configuration (recommended [`asset modules`](https://webpack.js.org/guides/asset-modules/)).
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`, `manifest`, `prefetch`, `preload` or when the `itemprop` attribute is `image`, `logo`, `screenshot`, `thumbnailurl`, `contenturl`, `downloadurl`, `duringmedia`, `embedurl`, `installurl`, `layoutimage`
- the `imagesrcset` 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`, `manifest`, `prefetch`, `preload`
- the `content` attribute of the `meta` tag when the `name` attribute is `msapplication-tileimage`, `msapplication-square70x70logo`, `msapplication-square150x150logo`, `msapplication-wide310x150logo`, `msapplication-square310x310logo`, `msapplication-config`, `twitter:image` 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` or when the `itemprop` attribute is `image`, `logo`, `screenshot`, `thumbnailurl`, `contenturl`, `downloadurl`, `duringmedia`, `embedurl`, `installurl`, `layoutimage`
- the `icon-uri` value component in `content` attribute of the `meta` tag when the `name` attribute is `msapplication-task`
#### `boolean`
The `true` value enables the processing of all default elements and attributes, the `false` value disables the processing of all attributes.
**webpack.config.js**
```js
module.exports = {
module: {
rules: [
{
test: /\.html$/i,
loader: "html-loader",
options: {
// Disables attributes processing
sources: false,
},
},
],
},
};
```
#### `object`
Allows you to specify which tags and attributes to process, filter them, filter urls and process sources starting with `/`.
For example:
**webpack.config.js**
```js
module.exports = {
module: {
rules: [
{
test: /\.html$/i,
loader: "html-loader",
options: {
sources: {
list: [
// All default supported tags and attributes
"...",
{
tag: "img",
attribute: "data-src",
type: "src",
},
{
tag: "img",
attribute: "data-srcset",
type: "srcset",
},
],
urlFilter: (attribute, value, resourcePath) => {
// The `attribute` argument contains a name of the HTML attribute.
// The `value` argument contains a value of the HTML attribute.
// The `resourcePath` argument contains a path to the loaded HTML file.
if (/example\.pdf$/.test(value)) {
return false;
}
return true;
},
},
},
},
],
},
};
```
#### `list`
Type:
```ts
type list = Array<{
tag?: string;
attribute?: string;
type?: string;
filter?: (
tag: string,
attribute: string,
attributes: string,
resourcePath: string,
) => boolean;
}>;
```
Default: [supported tags and attributes](#sources).
Allows to setup which tags and attributes to process and how, as well as the ability to filter some of them.
Using `...` syntax allows you to extend [default supported tags and attributes](#sources).
For example:
**webpack.config.js**
```js
module.exports = {
module: {
rules: [
{
test: /\.html$/i,
loader: "html-loader",
options: {
sources: {
list: [
// All default supported tags and attributes
"...",
{
tag: "img",
attribute: "data-src",
type: "src",
},
{
tag: "img",
attribute: "data-srcset",
type: "srcset",
},
{
// Tag name
tag: "link",
// Attribute name
attribute: "href",
// Type of processing, can be `src` or `scrset`
type: "src",
// Allow to filter some attributes
filter: (tag, attribute, attributes, resourcePath) => {
// The `tag` argument contains a name of the HTML tag.
// The `attribute` argument contains a name of the HTML attribute.
// The `attributes` argument contains all attributes of the tag.
// The `resourcePath` argument contains a path to the loaded HTML file.
if (/my-html\.html$/.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**
```js
module.exports = {
module: {
rules: [
{
test: /\.html$/i,
loader: "html-loader",
options: {
sources: {
list: [
{
// Attribute name
attribute: "src",
// Type of processing, can be `src` or `scrset`
type: "src",
// Allow to filter some attributes (optional)
filter: (tag, attribute, attributes, resourcePath) => {
// The `tag` argument contains a name of the HTML tag.
// The `attribute` argument contains a name of the HTML attribute.
// The `attributes` argument contains all attributes of the tag.
// The `resourcePath` argument contains a path to the loaded HTML file.
// choose all HTML tags except img tag
return tag.toLowerCase() !== "img";
},
},
],
},
},
},
],
},
};
```
Filter can also be used to extend the supported elements and attributes.
For example, filter can help process meta tags that reference assets:
```js
module.exports = {
module: {
rules: [
{
test: /\.html$/i,
loader: "html-loader",
options: {
sources: {
list: [
{
tag: "meta",
attribute: "content",
type: "src",
filter: (tag, attribute, attributes, resourcePath) => {
if (
attributes.value === "og:image" ||
attributes.name === "twitter:image"
) {
return true;
}
return false;
},
},
],
},
},
},
],
},
};
```
> [!NOTE]
>
> source with a `tag` option takes precedence over source without.
Filter can be used to disable default sources.
For example:
```js
module.exports = {
module: {
rules: [
{
test: /\.html$/i,
loader: "html-loader",
options: {
sources: {
list: [
"...",
{
tag: "img",
attribute: "src",
type: "src",
filter: () => false,
},
],
},
},
},
],
},
};
```
#### `urlFilter`
Type:
```ts
type urlFilter = (
attribute: string,
value: string,
resourcePath: string,
) => boolean;
```
Default: `undefined`
Allow to filter urls. All filtered urls will not be resolved (left in the code as they were written).
Non-requestable sources (for example `<img src="javascript:void(0)">`) are not handled by default.
```js
module.exports = {
module: {
rules: [
{
test: /\.html$/i,
loader: "html-loader",
options: {
sources: {
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$/.test(value)) {
return false;
}
return true;
},
},
},
},
],
},
};
```
#### `scriptingEnabled`
Type:
```ts
type scriptingEnabled = boolean;
```
Default: `true`
By default, the parser in `html-loader` interprets content inside `<noscript>` tags as `#text`, so processing of content inside this tag will be ignored.
In order to enable processing inside `<noscript>` for content recognition by the parser as `#AST`, set this parameter to: `false`
Additional information: [scriptingEnabled](https://parse5.js.org/interfaces/parse5.ParserOptions.html#scriptingEnabled)
**webpack.config.js**
```js
module.exports = {
module: {
rules: [
{
test: /\.html$/i,
loader: "html-loader",
options: {
sources: {
// Enables processing inside the <noscript> tag
scriptingEnabled: false,
},
},
},
],
},
};
```
### `preprocessor`
Type:
```ts
type preprocessor = (content: string, loaderContext: LoaderContext) => string;
```
Default: `undefined`
Allows pre-processing of content before handling.
> [!WARNING]
>
> You should always return valid HTML
**file.hbs**
```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**
```js
const Handlebars = require("handlebars");
module.exports = {
module: {
rules: [
{
test: /\.hbs$/i,
loader: "html-loader",
options: {
preprocessor: (content, loaderContext) => {
let result;
try {
result = Handlebars.compile(content)({
firstname: "Value",
lastname: "OtherValue",
});
} catch (error) {
loaderContext.emitError(error);
return content;
}
return result;
},
},
},
],
},
};
```
You can also set the `preprocessor` option as an asynchronous function instance.
For example:
**webpack.config.js**
```js
const Handlebars = require("handlebars");
module.exports = {
module: {
rules: [
{
test: /\.hbs$/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;
},
},
},
],
},
};
```
### `postprocessor`
Type:
```ts
type postprocessor = (content: string, loaderContext: LoaderContext) => string;
```
Default: `undefined`
Allows post-processing of content after replacing all attributes (like `src`/`srcset`/etc).
**file.html**
```html
<img src="image.png" />
<img src="<%= 'Hello ' + (1+1) %>" />
<img src="<%= require('./image.png') %>" />
<img src="<%= new URL('./image.png', import.meta.url) %>" />
<div><%= require('./gallery.html').default %></div>
```
#### `function`
You can set the `postprocessor` option as a `function` instance.
**webpack.config.js**
```js
const Handlebars = require("handlebars");
module.exports = {
module: {
rules: [
{
test: /\.html$/i,
loader: "html-loader",
options: {
postprocessor: (content, loaderContext) => {
// When you environment supports template literals (using browserslist or options) we will generate code using them
const isTemplateLiteralSupported = content[0] === "`";
return content
.replace(/<%=/g, isTemplateLiteralSupported ? `\${` : '" +')
.replace(/%>/g, isTemplateLiteralSupported ? "}" : '+ "');
},
},
},
],
},
};
```
You can also set the `postprocessor` option as an asynchronous function instance.
For example:
**webpack.config.js**
```js
const Handlebars = require("handlebars");
module.exports = {
module: {
rules: [
{
test: /\.hbs$/i,
loader: "html-loader",
options: {
postprocessor: async (content, loaderContext) => {
const value = await getValue();
// When you environment supports template literals (using browserslist or options) we will generate code using them
const isTemplateLiteralSupported = content[0] === "`";
return content
.replace(/<%=/g, isTemplateLiteralSupported ? `\${` : '" +')
.replace(/%>/g, isTemplateLiteralSupported ? "}" : '+ "')
.replace("my-value", value);
},
},
},
],
},
};
```
### `minimize`
Type:
```ts
type minimize =
| boolean
| {
caseSensitive?: boolean;
collapseWhitespace?: boolean;
conservativeCollapse?: boolean;
keepClosingSlash?: boolean;
minifyCSS?: boolean;
minifyJS?: boolean;
removeComments?: boolean;
removeRedundantAttributes?: boolean;
removeScriptTypeAttributes?: boolean;
removeStyleLinkTypeAttributes?: boolean;
};
```
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:
```js
({
caseSensitive: true,
collapseWhitespace: true,
conservativeCollapse: true,
keepClosingSlash: true,
minifyCSS: true,
minifyJS: true,
removeComments: true,
removeRedundantAttributes: true,
removeScriptTypeAttributes: true,
removeStyleLinkTypeAttributes: true,
});
```
**webpack.config.js**
```js
module.exports = {
module: {
rules: [
{
test: /\.html$/i,
loader: "html-loader",
options: {
minimize: true,
},
},
],
},
};
```
#### `object`
**webpack.config.js**
See [html-minifier-terser](https://github.com/DanielRuf/html-minifier-terser)'s documentation for more information on the available options.
The default rules can be overridden using the following options in your `webpack.conf.js`
**webpack.config.js**
```js
module.exports = {
module: {
rules: [
{
test: /\.html$/i,
loader: "html-loader",
options: {
minimize: {
removeComments: false,
collapseWhitespace: false,
},
},
},
],
},
};
```
The default rules can be extended:
**webpack.config.js**
```js
const { defaultMinimizerOptions } = require("html-loader");
module.exports = {
module: {
rules: [
{
test: /\.html$/i,
loader: "html-loader",
options: {
minimize: {
...defaultMinimizerOptions,
removeComments: false,
collapseWhitespace: false,
},
},
},
],
},
};
```
### `esModule`
Type:
```ts
type esModule = boolean;
```
Default: `true`
By default, `html-loader` generates JS modules that use the ES modules syntax.
There are some cases in which using ES modules is beneficial, such as [module concatenation](https://webpack.js.org/plugins/module-concatenation-plugin/) and [tree shaking](https://webpack.js.org/guides/tree-shaking/).
You can enable a CommonJS modules syntax using:
**webpack.config.js**
```js
module.exports = {
module: {
rules: [
{
test: /\.html$/i,
loader: "html-loader",
options: {
esModule: false,
},
},
],
},
};
```
## Examples
### Disable url resolving using the `<!-- webpackIgnore: true -->` comment
With `<!-- webpackIgnore: true -->` comment, one can disable sources handling for next tag.
```html
<!-- Disabled url handling for the src attribute -->
<!-- webpackIgnore: true -->
<img src="image.png" />
<!-- Disabled url handling for the src and srcset attributes -->
<!-- webpackIgnore: true -->
<img
srcset="image.png 480w, image.png 768w"
src="image.png"
alt="Elva dressed as a fairy"
/>
<!-- Disabled url handling for the content attribute -->
<!-- webpackIgnore: true -->
<meta itemprop="image" content="./image.png" />
<!-- Disabled url handling for the href attribute -->
<!-- webpackIgnore: true -->
<link rel="icon" type="image/png" sizes="192x192" href="./image.png" />
```
### roots
With [`resolve.roots`](https://webpack.js.org/configuration/resolve/#resolveroots) one can specify a list of directories where requests of server-relative URLs (starting with '/') are resolved.
**webpack.config.js**
```js
module.exports = {
context: __dirname,
module: {
rules: [
{
test: /\.html$/i,
loader: "html-loader",
options: {},
},
{
test: /\.jpg$/,
type: "asset/resource",
},
],
},
resolve: {
roots: [path.resolve(__dirname, "fixtures")],
},
};
```
**file.html**
```html
<img src="/image.jpg" />
```
```js
// => image.jpg in __dirname/fixtures will be resolved
```
### CDN
**webpack.config.js**
```js
module.exports = {
module: {
rules: [
{
test: /\.jpg$/,
type: "asset/resource",
},
{
test: /\.png$/,
type: "asset/inline",
},
],
},
output: {
publicPath: "http://cdn.example.com/[fullhash]/",
},
};
```
**file.html**
```html
<img src="image.jpg" data-src="image2x.png" />
```
**index.js**
```js
require("html-loader!./file.html");
// => '<img src="http://cdn.example.com/49eba9f/a992ca.jpg" data-src="image2x.png">'
```
```js
require('html-loader?{"sources":{"list":[{"tag":"img","attribute":"data-src","type":"src"}]}}!./file.html');
// => '<img src="image.jpg" data-src="data:image/png;base64,..." >'
```
```js
require('html-loader?{"sources":{"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,..." >'
```
### Process `script` and `link` tags
**script.file.js**
```js
console.log(document);
```
**style.file.css**
```css
a {
color: red;
}
```
**file.html**
```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**
```js
module.exports = {
module: {
rules: [
{
test: /\.html$/,
type: "asset/resource",
generator: {
filename: "[name][ext]",
},
},
{
test: /\.html$/i,
use: ["html-loader"],
},
{
test: /\.js$/i,
exclude: /\.file.js$/i,
loader: "babel-loader",
},
{
test: /\.file.js$/i,
type: "asset/resource",
},
{
test: /\.css$/i,
exclude: /\.file.css$/i,
loader: "css-loader",
},
{
test: /\.file.css$/i,
type: "asset/resource",
},
],
},
};
```
### Templating
You can use any template system. Below is an example for [handlebars](https://handlebarsjs.com/).
**file.hbs**
```hbs
<div>
<p>{{firstname}} {{lastname}}</p>
<img src="image.png" alt="alt" />
<div>
```
**webpack.config.js**
```js
const Handlebars = require("handlebars");
module.exports = {
module: {
rules: [
{
test: /\.hbs$/i,
loader: "html-loader",
options: {
preprocessor: (content, loaderContext) => {
let result;
try {
result = Handlebars.compile(content)({
firstname: "Value",
lastname: "OtherValue",
});
} catch (error) {
loaderContext.emitError(error);
return content;
}
return result;
},
},
},
],
},
};
```
### PostHTML
You can use [PostHTML](https://github.com/posthtml/posthtml) without any additional loaders.
**file.html**
```html
<img src="image.jpg" />
```
**webpack.config.js**
```js
const posthtml = require("posthtml");
const posthtmlWebp = require("posthtml-webp");
module.exports = {
module: {
rules: [
{
test: /\.hbs$/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 html-loader and [`asset modules`](https://webpack.js.org/guides/asset-modules/).
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 [`asset modules`](https://webpack.js.org/guides/asset-modules/)
will write the _.html_ file for you. Example:
**webpack.config.js**
```js
module.exports = {
output: {
assetModuleFilename: "[name][ext]",
},
module: {
rules: [
{
test: /\.html$/,
type: "asset/resource",
generator: {
filename: "[name][ext]",
},
},
{
test: /\.html$/i,
use: ["html-loader"],
},
],
},
};
```
## Contributing
Please take a moment to read our contributing guidelines if you haven't yet done so.
[CONTRIBUTING](./.github/CONTRIBUTING.md)
## License
[MIT](./LICENSE)
[npm]: https://img.shields.io/npm/v/html-loader.svg
[npm-url]: https://npmjs.com/package/html-loader
[node]: https://img.shields.io/node/v/html-loader.svg
[node-url]: https://nodejs.org
[tests]: https://github.com/webpack-contrib/html-loader/workflows/html-loader/badge.svg
[tests-url]: https://github.com/webpack-contrib/html-loader/actions
[cover]: https://codecov.io/gh/webpack-contrib/html-loader/branch/master/graph/badge.svg
[cover-url]: https://codecov.io/gh/webpack-contrib/html-loader
[discussion]: https://img.shields.io/github/discussions/webpack/webpack
[discussion-url]: https://github.com/webpack/webpack/discussions
[size]: https://packagephobia.now.sh/badge?p=html-loader
[size-url]: https://packagephobia.now.sh/result?p=html-loader