hugo/docs/content/en/content-management/syntax-highlighting.md
2020-08-14 18:31:40 +02:00

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---
title: Syntax Highlighting
description: Hugo comes with really fast syntax highlighting from Chroma.
date: 2017-02-01
publishdate: 2017-02-01
keywords: [highlighting,chroma,code blocks,syntax]
categories: [content management]
menu:
docs:
parent: "content-management"
weight: 300
weight: 20
sections_weight: 20
draft: false
aliases: [/extras/highlighting/,/extras/highlight/,/tools/syntax-highlighting/]
toc: true
---
Hugo uses [Chroma](https://github.com/alecthomas/chroma) as its code highlighter; it is built in Go and is really, really fast -- and for the most important parts compatible with Pygments we used before.
## Configure Syntax Highlighter
See [Configure Highlight](/getting-started/configuration-markup#highlight).
## Generate Syntax Highlighter CSS
If you run with `pygmentsUseClasses=true` in your site config, you need a style sheet.
You can generate one with Hugo:
```bash
hugo gen chromastyles --style=monokai > syntax.css
```
Run `hugo gen chromastyles -h` for more options. See https://xyproto.github.io/splash/docs/ for a gallery of available styles.
## Highlight Shortcode
Highlighting is carried out via the [built-in shortcode](/content-management/shortcodes/) `highlight`. `highlight` takes exactly one required parameter for the programming language to be highlighted and requires a closing shortcode. Note that `highlight` is *not* used for client-side javascript highlighting.
Options:
* `linenos`: configure line numbers. Valid values are `true`, `false`, `table`, or `inline`. `false` will turn off line numbers if it's configured to be on in site config. {{< new-in "0.60.0" >}} `table` will give copy-and-paste friendly code blocks.
* `hl_lines`: lists a set of line numbers or line number ranges to be highlighted.
* `linenostart=199`: starts the line number count from 199.
### Example: Highlight Shortcode
```
{{</* highlight go "linenos=table,hl_lines=8 15-17,linenostart=199" */>}}
// ... code
{{</* / highlight */>}}
```
Gives this:
{{< highlight go "linenos=table,hl_lines=8 15-17,linenostart=199" >}}
// GetTitleFunc returns a func that can be used to transform a string to
// title case.
//
// The supported styles are
//
// - "Go" (strings.Title)
// - "AP" (see https://www.apstylebook.com/)
// - "Chicago" (see https://www.chicagomanualofstyle.org/home.html)
//
// If an unknown or empty style is provided, AP style is what you get.
func GetTitleFunc(style string) func(s string) string {
switch strings.ToLower(style) {
case "go":
return strings.Title
case "chicago":
return transform.NewTitleConverter(transform.ChicagoStyle)
default:
return transform.NewTitleConverter(transform.APStyle)
}
}
{{< / highlight >}}
## Highlight Template Func
See [Highlight](/functions/highlight/).
## Highlighting in Code Fences
Highlighting in code fences is enabled by default.{{< new-in "0.60.0" >}}
````
```go {linenos=table,hl_lines=[8,"15-17"],linenostart=199}
// ... code
```
````
Gives this:
```go {linenos=table,hl_lines=[8,"15-17"],linenostart=199}
// GetTitleFunc returns a func that can be used to transform a string to
// title case.
//
// The supported styles are
//
// - "Go" (strings.Title)
// - "AP" (see https://www.apstylebook.com/)
// - "Chicago" (see https://www.chicagomanualofstyle.org/home.html)
//
// If an unknown or empty style is provided, AP style is what you get.
func GetTitleFunc(style string) func(s string) string {
switch strings.ToLower(style) {
case "go":
return strings.Title
case "chicago":
return transform.NewTitleConverter(transform.ChicagoStyle)
default:
return transform.NewTitleConverter(transform.APStyle)
}
}
```
{{< new-in "0.60.0" >}}Note that only Goldmark supports passing attributes such as `hl_lines`, and it's important that it does not contain any spaces. See [goldmark-highlighting](https://github.com/yuin/goldmark-highlighting) for more information.
The options are the same as in the [highlighting shortcode](/content-management/syntax-highlighting/#highlight-shortcode),including `linenos=false`, but note the slightly different Markdown attribute syntax.
## List of Chroma Highlighting Languages
The full list of Chroma lexers and their aliases (which is the identifier used in the `highlight` template func or when doing highlighting in code fences):
{{< chroma-lexers >}}
[Prism]: https://prismjs.com
[prismdownload]: https://prismjs.com/download.html
[Highlight.js]: https://highlightjs.org/
[Rainbow]: https://craig.is/making/rainbows
[Syntax Highlighter]: https://alexgorbatchev.com/SyntaxHighlighter/
[Google Prettify]: https://github.com/google/code-prettify
[Yandex]: https://yandex.ru/