# Highlight.js
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---
### :warning: :warning: Important: Version 9 is no longer supported. :warning: :warning:
Version 9 has reached end-of-support and will receive no future updates.
It may include unpatched security vulnerabiites. Please upgrade to version 10.
*The last release was 9.18.4 on November 18, 2020.*
Please see [VERSION_10_UPGRADE.md](https://github.com/highlightjs/highlight.js/blob/master/VERSION_10_UPGRADE.md) and perhaps [SECURITY.md](https://github.com/highlightjs/highlight.js/blob/master/SECURITY.md).
---
Highlight.js is a syntax highlighter written in JavaScript. It works in
the browser as well as on the server. It works with pretty much any
markup, doesn’t depend on any framework, and has automatic language
detection.
## Getting Started
The bare minimum for using highlight.js on a web page is linking to the
library along with one of the styles and calling
[`initHighlightingOnLoad`][1]:
```html
```
This will find and highlight code inside of `
` tags; it tries
to detect the language automatically. If automatic detection doesn’t
work for you, you can specify the language in the `class` attribute:
```html
...
```
Classes may also be prefixed with either `language-` or `lang-`.
```html
...
```
### Plaintext and Disabling Highlighting
To style arbitrary text like code, but without any highlighting, use the
`plaintext` class:
```html
...
```
To disable highlighting of a tag completely, use the `nohighlight` class:
```html
` to mark up your code. If
you don't use a container that preserves line breaks you will need to
configure highlight.js to use the ` ` tag:
```js
hljs.configure({useBR: true});
document.querySelectorAll('div.code').forEach((block) => {
hljs.highlightBlock(block);
});
```
For other options refer to the documentation for [`configure`][4].
## Web Workers
You can run highlighting inside a web worker to avoid freezing the browser
window while dealing with very big chunks of code.
In your main script:
```js
addEventListener('load', () => {
const code = document.querySelector('#code');
const worker = new Worker('worker.js');
worker.onmessage = (event) => { code.innerHTML = event.data; }
worker.postMessage(code.textContent);
});
```
In worker.js:
```js
onmessage = (event) => {
importScripts('/highlight.pack.js');
const result = self.hljs.highlightAuto(event.data);
postMessage(result.value);
};
```
## Node.js
You can use highlight.js with node to highlight content before sending it to the browser.
Make sure to use the `.value` property to get the formatted html.
For more info about the returned object refer to the api docs https://highlightjs.readthedocs.io/en/latest/api.html
```js
// require the highlight.js library including all languages
const hljs = require('./highlight.js');
const highlightedCode = hljs.highlightAuto('Hello World!').value
```
```js
// require the highlight.js library without languages
const hljs = require("highlight.js/lib/highlight.js");
// separately require languages
hljs.registerLanguage('html', require('highlight.js/lib/languages/html'));
hljs.registerLanguage('sql', require('highlight.js/lib/languages/sql'));
// highlight with providing the language
const highlightedCode = hljs.highlight('html', 'Hello World!').value
```
## Getting the Library
You can get highlight.js as a hosted, or custom-build, browser script or
as a server module. Right out of the box the browser script supports
both AMD and CommonJS, so if you wish you can use RequireJS or
Browserify without having to build from source. The server module also
works perfectly fine with Browserify, but there is the option to use a
build specific to browsers rather than something meant for a server.
Head over to the [download page][5] for all the options.
**Don't link to GitHub directly.** The library is not supposed to work straight
from the source, it requires building. If none of the pre-packaged options
work for you refer to the [building documentation][6].
**The CDN-hosted package doesn't have all the languages.** Otherwise it'd be
too big. If you don't see the language you need in the ["Common" section][5],
it can be added manually:
```html
```
**On Almond.** You need to use the optimizer to give the module a name. For
example:
```bash
r.js -o name=hljs paths.hljs=/path/to/highlight out=highlight.js
```
### CommonJS
You can import Highlight.js as a CommonJS-module:
```bash
npm install highlight.js --save
```
In your application:
```js
import hljs from 'highlight.js';
```
The default import imports all languages! Therefore it is likely to be more efficient to import only the library and the languages you need:
```js
import hljs from 'highlight.js/lib/highlight';
import javascript from 'highlight.js/lib/languages/javascript';
hljs.registerLanguage('javascript', javascript);
```
To set the syntax highlighting style, if your build tool processes CSS from your JavaScript entry point, you can import the stylesheet directly into your CommonJS-module:
```js
import hljs from 'highlight.js/lib/highlight';
import 'highlight.js/styles/github.css';
```
## License
Highlight.js is released under the BSD License. See [LICENSE][7] file
for details.
## Links
The official site for the library is at .
Further in-depth documentation for the API and other topics is at
.
Authors and contributors are listed in the [AUTHORS.txt][8] file.
[1]: http://highlightjs.readthedocs.io/en/latest/api.html#inithighlightingonload
[2]: http://highlightjs.readthedocs.io/en/latest/css-classes-reference.html
[3]: http://highlightjs.readthedocs.io/en/latest/api.html#highlightblock-block
[4]: http://highlightjs.readthedocs.io/en/latest/api.html#configure-options
[5]: https://highlightjs.org/download/
[6]: http://highlightjs.readthedocs.io/en/latest/building-testing.html
[7]: https://github.com/highlightjs/highlight.js/blob/master/LICENSE
[8]: https://github.com/highlightjs/highlight.js/blob/master/AUTHORS.txt