372 lines
14 KiB
Markdown
372 lines
14 KiB
Markdown
# Highlight.js
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[](https://www.npmjs.com/package/highlight.js)
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[](https://join.slack.com/t/highlightjs/shared_invite/zt-mj0utgqp-TNFf4VQICnDnPg4zMHChFw)
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[](https://discord.gg/M24EbU7ja9)
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[](https://github.com/highlightjs/highlight.js/blob/main/LICENSE)
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[](https://packagephobia.now.sh/result?p=highlight.js)
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[](https://www.npmjs.com/package/highlight.js)
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[](https://www.jsdelivr.com/package/gh/highlightjs/cdn-release)
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[](https://lgtm.com/projects/g/highlightjs/highlight.js/?mode=list)
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[](https://github.com/highlightjs/highlight.js/actions?query=workflow%3A%22Node.js+CI%22)
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[](https://github.com/highlightjs/highlight.js/issues)
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[](https://github.com/highlightjs/highlight.js/issues?q=is%3Aopen+is%3Aissue+label%3A%22help+welcome%22)
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[](https://github.com/highlightjs/highlight.js/issues?q=is%3Aopen+is%3Aissue+label%3A%22beginner+friendly%22)
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[](https://snyk.io/test/github/highlightjs/highlight.js?targetFile=package.json)
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<!-- [](https://github.com/highlightjs/highlight.js/actions?query=workflow%3A%22Node.js+CI%22) -->
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<!-- [](https://github.com/highlightjs/highlight.js/commits/main) -->
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<!-- [](https://www.jsdelivr.com/package/gh/highlightjs/cdn-release) -->
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<!-- []() -->
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<!-- [](https://bundlephobia.com/result?p=highlight.js) -->
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Highlight.js is a syntax highlighter written in JavaScript. It works in
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the browser as well as on the server. It works with pretty much any
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markup, doesn’t depend on any framework, and has automatic language
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detection.
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#### Upgrading to Version 10
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Version 10 is one of the biggest releases in quite some time. If you're
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upgrading from version 9, there are some breaking changes and things you may
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want to double check first.
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Please read [VERSION_10_UPGRADE.md](https://github.com/highlightjs/highlight.js/blob/main/VERSION_10_UPGRADE.md) for high-level summary of breaking changes and any actions you may need to take. See [VERSION_10_BREAKING_CHANGES.md](https://github.com/highlightjs/highlight.js/blob/main/VERSION_10_BREAKING_CHANGES.md) for a more detailed list and [CHANGES.md](https://github.com/highlightjs/highlight.js/blob/main/CHANGES.md) to learn what else is new.
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##### Support for older versions
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Please see [SECURITY.md](https://github.com/highlightjs/highlight.js/blob/main/SECURITY.md) for support information.
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## Getting Started
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The bare minimum for using highlight.js on a web page is linking to the
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library along with one of the styles and calling [`highlightAll`][1]:
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```html
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<link rel="stylesheet" href="/path/to/styles/default.css">
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<script src="/path/to/highlight.min.js"></script>
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<script>hljs.highlightAll();</script>
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```
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This will find and highlight code inside of `<pre><code>` tags; it tries
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to detect the language automatically. If automatic detection doesn’t
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work for you, you can specify the language in the `class` attribute:
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```html
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<pre><code class="html">...</code></pre>
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```
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Classes may also be prefixed with either `language-` or `lang-`.
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```html
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<pre><code class="language-html">...</code></pre>
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```
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### Plaintext and Disabling Highlighting
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To style arbitrary text like code, but without any highlighting, use the
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`plaintext` class:
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```html
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<pre><code class="plaintext">...</code></pre>
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```
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To disable highlighting of a tag completely, use the `nohighlight` class:
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```html
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<pre><code class="nohighlight">...</code></pre>
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```
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### Supported Languages
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Highlight.js supports over 180 different languages in the core library. There are also 3rd party
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language plugins available for additional languages. You can find the full list of supported languages
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in [SUPPORTED_LANGUAGES.md][9].
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## Custom Scenarios
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When you need a bit more control over the initialization of
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highlight.js, you can use the [`highlightBlock`][3] and [`configure`][4]
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functions. This allows you to better control *what* to highlight and *when*.
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Here’s the equivalent of calling [`highlightAll`][1] using
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only vanilla JS:
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```js
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document.addEventListener('DOMContentLoaded', (event) => {
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document.querySelectorAll('pre code').forEach((block) => {
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hljs.highlightBlock(block);
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});
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});
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```
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Please refer to the documentation for [`configure`][4] options.
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### Using custom HTML elements for code blocks
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We strongly recommend `<pre><code>` wrapping for code blocks. It's quite
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semantic and "just works" out of the box with zero fiddling. It is possible to
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use other HTML elements (or combos), but you may need to pay special attention to
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preserving linebreaks.
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Let's say your markup for code blocks uses divs:
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```html
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<div class='code'>...</div>
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```
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To highlight such blocks manually:
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```js
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// first, find all the div.code blocks
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document.querySelectorAll('div.code').forEach(block => {
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// then highlight each
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hljs.highlightBlock(block);
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});
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```
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Without using a tag that preserves linebreaks (like `pre`) you'll need some
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additional CSS to help preserve them. You could also [pre and post-process line
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breaks with a plug-in][brPlugin], but *we recommend using CSS*.
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[brPlugin]: https://github.com/highlightjs/highlight.js/issues/2559
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To preserve linebreaks inside a `div` using CSS:
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```css
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div.code {
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white-space: pre;
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}
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```
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## Using with Vue.js
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Simply register the plugin with Vue:
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```js
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Vue.use(hljs.vuePlugin);
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```
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And you'll be provided with a `highlightjs` component for use
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in your templates:
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```html
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<div id="app">
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<!-- bind to a data property named `code` -->
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<highlightjs autodetect :code="code" />
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<!-- or literal code works as well -->
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<highlightjs language='javascript' code="var x = 5;" />
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</div>
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```
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## Web Workers
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You can run highlighting inside a web worker to avoid freezing the browser
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window while dealing with very big chunks of code.
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In your main script:
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```js
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addEventListener('load', () => {
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const code = document.querySelector('#code');
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const worker = new Worker('worker.js');
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worker.onmessage = (event) => { code.innerHTML = event.data; }
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worker.postMessage(code.textContent);
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});
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```
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In worker.js:
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```js
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onmessage = (event) => {
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importScripts('<path>/highlight.min.js');
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const result = self.hljs.highlightAuto(event.data);
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postMessage(result.value);
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};
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```
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## Node.js
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You can use highlight.js with node to highlight content before sending it to the browser.
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Make sure to use the `.value` property to get the formatted html.
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For more info about the returned object refer to the [api docs](https://highlightjs.readthedocs.io/en/latest/api.html).
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```js
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// require the highlight.js library, including all languages
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const hljs = require('./highlight.js');
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const highlightedCode = hljs.highlightAuto('<span>Hello World!</span>').value
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```
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Or for a smaller footprint... load just the languages you need.
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```js
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const hljs = require('highlight.js/lib/core'); // require only the core library
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// separately require languages
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hljs.registerLanguage('xml', require('highlight.js/lib/languages/xml'));
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const highlightedCode = hljs.highlight('<span>Hello World!</span>', {language: 'xml'}).value
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```
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## ES6 Modules
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First, you'll likely install via `npm` or `yarn` -- see [Getting the Library](#getting-the-library) below.
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In your application:
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```js
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import hljs from 'highlight.js';
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```
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The default import imports all languages. Therefore it is likely to be more efficient to import only the library and the languages you need:
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```js
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import hljs from 'highlight.js/lib/core';
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import javascript from 'highlight.js/lib/languages/javascript';
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hljs.registerLanguage('javascript', javascript);
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```
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To set the syntax highlighting style, if your build tool processes CSS from your JavaScript entry point, you can also import the stylesheet directly as modules:
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```js
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import hljs from 'highlight.js/lib/core';
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import 'highlight.js/styles/github.css';
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```
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## Getting the Library
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You can get highlight.js as a hosted, or custom-build, browser script or
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as a server module. Right out of the box the browser script supports
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both AMD and CommonJS, so if you wish you can use RequireJS or
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Browserify without having to build from source. The server module also
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works perfectly fine with Browserify, but there is the option to use a
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build specific to browsers rather than something meant for a server.
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**Do not link to GitHub directly.** The library is not supposed to work straight
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from the source, it requires building. If none of the pre-packaged options
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work for you refer to the [building documentation][6].
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**On Almond.** You need to use the optimizer to give the module a name. For
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example:
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```bash
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r.js -o name=hljs paths.hljs=/path/to/highlight out=highlight.js
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```
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### CDN Hosted
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A prebuilt version of Highlight.js bundled with many common languages is hosted by several popular CDNs.
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When using Highlight.js via CDN you can use Subresource Integrity for additional security. For details
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see [DIGESTS.md](https://github.com/highlightjs/cdn-release/blob/main/DIGESTS.md).
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**cdnjs** ([link](https://cdnjs.com/libraries/highlight.js))
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```html
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<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/10.7.3/styles/default.min.css">
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<script src="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/10.7.3/highlight.min.js"></script>
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<!-- and it's easy to individually load additional languages -->
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<script src="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/10.7.3/languages/go.min.js"></script>
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```
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**jsdelivr** ([link](https://www.jsdelivr.com/package/gh/highlightjs/cdn-release))
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```html
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<link rel="stylesheet" href="https://cdn.jsdelivr.net/gh/highlightjs/cdn-release@10.7.3/build/styles/default.min.css">
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<script src="https://cdn.jsdelivr.net/gh/highlightjs/cdn-release@10.7.3/build/highlight.min.js"></script>
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<!-- and it's easy to individually load additional languages -->
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<script src="https://cdn.jsdelivr.net/gh/highlightjs/cdn-release@10.7.3/build/languages/go.min.js"></script>
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```
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**unpkg** ([link](https://unpkg.com/browse/@highlightjs/cdn-assets/))
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```html
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<link rel="stylesheet" href="https://unpkg.com/@highlightjs/cdn-assets@10.7.3/styles/default.min.css">
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<script src="https://unpkg.com/@highlightjs/cdn-assets@10.7.3/highlight.min.js"></script>
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<!-- and it's easy to individually load additional languages -->
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<script src="https://unpkg.com/@highlightjs/cdn-assets@10.7.3/languages/go.min.js"></script>
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```
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**Note:** *The CDN-hosted `highlight.min.js` package doesn't bundle every language.* It would be
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very large. You can find our list of "common" languages that we bundle by default on our [download page][5].
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### Self Hosting
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The [download page][5] can quickly generate a custom bundle including only the languages you need.
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Alternatively, you can build a browser package from [source](#source):
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```
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node tools/build.js -t browser :common
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```
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See our [building documentation][6] for more information.
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**Note:** Building from source should always result in the smallest size builds. The website download page is optimized for speed, not size.
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#### Prebuilt CDN assets
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You can also download and self-host the same assets we serve up via our own CDNs. We publish those builds to the [cdn-release](https://github.com/highlightjs/cdn-release) GitHub repository. You can easily pull individual files off the CDN endpoints with `curl`, etc; if say you only needed `highlight.min.js` and a single CSS file.
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There is also an npm package [@highlightjs/cdn-assets](https://www.npmjs.com/package/@highlightjs/cdn-assets) if pulling the assets in via `npm` or `yarn` would be easier for your build process.
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### NPM / Node.js server module
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Highlight.js can also be used on the server. The package with all supported languages can be installed from NPM or Yarn:
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```bash
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npm install highlight.js
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# or
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yarn add highlight.js
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```
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Alternatively, you can build it from [source](#source):
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```bash
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node tools/build.js -t node
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```
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See our [building documentation][6] for more information.
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### Source
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[Current source][10] is always available on GitHub.
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## License
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Highlight.js is released under the BSD License. See [LICENSE][7] file
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for details.
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## Links
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The official site for the library is at <https://highlightjs.org/>.
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Further in-depth documentation for the API and other topics is at
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<http://highlightjs.readthedocs.io/>.
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A list of the Core Team and contributors can be found in the [CONTRIBUTORS.md][8] file.
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[1]: http://highlightjs.readthedocs.io/en/latest/api.html#highlightall
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[2]: http://highlightjs.readthedocs.io/en/latest/css-classes-reference.html
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[3]: http://highlightjs.readthedocs.io/en/latest/api.html#highlightblock-block
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[4]: http://highlightjs.readthedocs.io/en/latest/api.html#configure-options
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[5]: https://highlightjs.org/download/
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[6]: http://highlightjs.readthedocs.io/en/latest/building-testing.html
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[7]: https://github.com/highlightjs/highlight.js/blob/main/LICENSE
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[8]: https://github.com/highlightjs/highlight.js/blob/main/CONTRIBUTORS.md
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[9]: https://github.com/highlightjs/highlight.js/blob/main/SUPPORTED_LANGUAGES.md
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[10]: https://github.com/highlightjs/
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