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Syntax Highlighting Plugin

Contents

A pack of Eleventy plugins for PrismJS syntax highlighting. No browser/client JavaScript here, these highlight transformations are all done at build-time. Supports individual line highlighting.

Installation Jump to heading

Available on npm.

npm install @11ty/eleventy-plugin-syntaxhighlight --save-dev

Open up your Eleventy config file (probably .eleventy.js) and use addPlugin:

Filename .eleventy.js
const syntaxHighlight = require("@11ty/eleventy-plugin-syntaxhighlight");

module.exports = function(eleventyConfig) {
  eleventyConfig.addPlugin(syntaxHighlight);
};
INFO:
You’re only allowed one module.exports in your configuration file, so make sure you only copy the require and the addPlugin lines above!

Optionally pass in an options object as the second argument to addPlugin to further customize this plugin pack.

Expand to see Advanced Options 
const syntaxHighlight = require("@11ty/eleventy-plugin-syntaxhighlight");

module.exports = function(eleventyConfig) {
  eleventyConfig.addPlugin(syntaxHighlight, {

    // Line separator for line breaks
    lineSeparator: "\n",

    // Change which Eleventy template formats use syntax highlighters
    templateFormats: ["*"], // default

    // Use only a subset of template types (11ty.js added in v4.0.0)
    // templateFormats: ["liquid", "njk", "md", "11ty.js"],

    // init callback lets you customize Prism
    init: function({ Prism }) {
      Prism.languages.myCustomLanguage = /* */;
    },

    // Added in 3.1.1, add HTML attributes to the <pre> or <code> tags
    preAttributes: {
      tabindex: 0,

      // Added in 4.1.0 you can use callback functions too
      "data-language": function({ language, content, options }) {
        return language;
      }
    },
    codeAttributes: {},

    // Added in 5.0.0, throw errors on invalid language names
    errorOnInvalidLanguage: false,
  });
};

You are responsible for including your favorite PrismJS theme CSS and there are many ways to do that. The default themes are provided by several CDNs and could be easily included in a base layout, like in the example below:

<html lang="en">
  <head>
    <!-- Some html boilerplate omitted -->
    <link href="https://unpkg.com/prismjs@1.20.0/themes/prism-okaidia.css" rel="stylesheet">
  </head>

You could also download the css file or paste its content inside a style tag. This approach allows the use of other themes from a Prism extension repository.

Usage Jump to heading

This plugin provides the following syntax highlighters using PrismJS, all of which currently support individual line highlighting.

Syntax Highlight Source Code Jump to heading

View this example in: Markdown WebC Liquid Nunjucks 11ty.js
Syntax Markdown
```js
function myFunction() {
  return true;
}
```

Optionally specify a language after the start of the markdown fenced code block.

Syntax Liquid
{% highlight js %}
function myFunction() {
  return true;
}
{% endhighlight %}
Syntax Nunjucks
{% highlight "js" %}
function myFunction() {
  return true;
}
{% endhighlight %}
Syntax 11ty.js
module.exports = function(data) {
  let code = `
function myFunction() {
  return true;
}`;

  return this.highlight("js", code);
}

The highlight JavaScript function was Added in Syntax Highlighter v4.0.0.

Syntax webc
<!-- Requires WebC v0.6.2+ -->
<!-- Requires Syntax Highlighter v4.2.0+ -->

<syntax-highlight language="js" webc:import="npm:@11ty/eleventy-plugin-syntaxhighlight">
function myFunction() {
  return true;
}
</syntax-highlight>
Expand to see an example of importing this as a global component in your configuration file.
Filename .eleventy.js
const pluginWebc = require("@11ty/eleventy-plugin-webc");

module.exports = function(eleventyConfig) {
	eleventyConfig.addPlugin(pluginWebc, {
		// Array `components` requires Eleventy WebC v0.9.2+
		components: [
			"_components/**/*.webc",
			"npm:@11ty/eleventy-plugin-syntaxhighlight/*.webc"
		]
	});
};
Filename page.webc
<syntax-highlight language="js">
function myFunction() {
  return true;
}
</syntax-highlight>
Expand to see an example of importing for use anywhere on the page via front matter.
Filename page.webc
---
webc:
  components: ./node_modules/@11ty/eleventy-plugin-syntaxhighlight/syntax-highlight.webc
---
<syntax-highlight language="js">
function myFunction() {
  return true;
}
</syntax-highlight>

Will render like this in the browser:

function myFunction() {
  return true;
}

Show changes using diff- syntax Jump to heading

Added in Syntax Highlighter v3.2.2

Add the diff- prefix to the language name on the previous examples to show code changes. Use a + or - at the beginning of the line to denote the addition or removal of that line.

View this example in: Markdown WebC Liquid Nunjucks 11ty.js
Syntax Markdown
```diff-js
+function myFunction() {
   // …
-  return true;
 }
```
Syntax Liquid
{% highlight diff-js %}
+function myFunction() {
   // …
-  return true;
 }
{% endhighlight %}
Syntax Nunjucks
{% highlight "diff-js" %}
+function myFunction() {
   // …
-  return true;
 }
{% endhighlight %}
Syntax 11ty.js
module.exports = function(data) {
  let code = `
+function myFunction() {
   // …
-  return true;
 }`;

  return this.highlight("diff-js", code);
}

The highlight JavaScript function was Added in Syntax Highlighter v4.0.0.

Syntax webc
<!-- Requires WebC v0.6.2+ -->
<!-- Requires Syntax Highlighter v4.2.0+ -->

<syntax-highlight language="diff-js" webc:import="npm:@11ty/eleventy-plugin-syntaxhighlight">
+function myFunction() {
   // …
-  return true;
 }
</syntax-highlight>

Will render like this in the browser:

+function myFunction() {
   // …
-  return true;
 }

Alternatively, you can use diff without another language name to enable plaintext line highlighting.

Don’t forget to add styles too! Here’s a sample diff- CSS
Syntax CSS
.token.deleted {
  background-color: hsl(350deg 100% 88% / 47%);
}
.token.inserted {
  background-color: hsl(120deg 73% 75% / 35%);
}

/* Make the + and - characters unselectable for copy/paste */
.token.prefix.unchanged,
.token.prefix.inserted,
.token.prefix.deleted {
	-webkit-user-select: none;
	user-select: none;
}

/* Optional: full-width background color */
.token.inserted:not(.prefix),
.token.deleted:not(.prefix) {
	display: block;
}
INFO:
Starting with v3.2 of this plugin, this plugin now bundles the official Prism diff-highlight plugin. The previous line highlighting feature is considered deprecated but still available. Check out the old documentation if you want to learn how to use the deprecated line-highlighting feature.

Other pages in Plugins: