Nunjucks

You can override a .njk file’s template engine. Read more at Changing a Template’s Rendering Engine.

Nunjucks Environment Options

We use Nunjucks defaults for all environment options (shown in the configure section of the Nunjucks docs).

Optional: Use your Nunjucks Environment Options Added in v1.0.0

It’s recommended to use the Configuration API to override the default Nunjucks options.

module.exports = function (eleventyConfig) {
	eleventyConfig.setNunjucksEnvironmentOptions({
		throwOnUndefined: true,
		autoescape: false, // warning: don’t do this!
	});
};

Advanced: Use your Nunjucks Environment

While it is preferred and simpler to use the Options-specific API method above (new in Eleventy 1.0!)—as an escape mechanism for advanced usage you may pass in your own instance of a Nunjucks Environment using the Configuration API.

let Nunjucks = require("nunjucks");

module.exports = function (eleventyConfig) {
	let nunjucksEnvironment = new Nunjucks.Environment(
		new Nunjucks.FileSystemLoader("_includes")
	);

	eleventyConfig.setLibrary("njk", nunjucksEnvironment);
};

Supported Features

Filters

Filters are used to transform or modify content. You can add Nunjucks specific filters, but you probably want to add a Universal filter instead.

Read more about Nunjucks Filter syntax.

module.exports = function(eleventyConfig) {
  // Nunjucks Filter
  eleventyConfig.addNunjucksFilter("myNjkFilter", function(value) { … });

  // Nunjucks Asynchronous Filter (read on below)
  eleventyConfig.addNunjucksAsyncFilter("myAsyncNjkFilter", function(value, callback) { … });

  // Universal filters (Adds to Liquid, Nunjucks, and Handlebars)
  eleventyConfig.addFilter("myFilter", function(value) { … });
};

Usage

<h1>{{ myVariable | myFilter }}</h1>

Multiple Filter Arguments

module.exports = function (eleventyConfig) {
	// Nunjucks Filter
	eleventyConfig.addNunjucksFilter(
		"concatThreeStrings",
		function (arg1, arg2, arg3) {
			return arg1 + arg2 + arg3;
		}
	);
};

<h1>{{ "first" | concatThreeThings("second", "third") }}</h1>

Asynchronous Nunjucks Filters

By default, almost all templating engines are synchronous. Nunjucks supports some asynchronous behavior, like filters. Here’s how that works:

module.exports = function (eleventyConfig) {
	eleventyConfig.addNunjucksAsyncFilter(
		"myAsyncFilter",
		function (value, callback) {
			setTimeout(function () {
				callback(null, "My Result");
			}, 100);
		}
	);
};

The last argument here is the callback function, the first argument of which is the error object and the second is the result data. Use this filter like you would any other: {{ myValue | myAsyncFilter }}.

Here’s a Nunjucks example with 2 arguments:

module.exports = function (eleventyConfig) {
	eleventyConfig.addNunjucksAsyncFilter(
		"myAsyncFilter",
		function (value1, value2, callback) {
			setTimeout(function () {
				callback(null, "My Result");
			}, 100);
		}
	);
};

Multi-argument filters in Nunjucks are called like this: {{ myValue1 | myAsyncFilter(myValue2) }}.

Shortcodes

Shortcodes are reusable bits of content. You can add Nunjucks specific shortcodes, but it’s probably easier to add a Universal shortcode instead.

Single Shortcode

module.exports = function(eleventyConfig) {
  // Nunjucks Shortcode
  eleventyConfig.addNunjucksShortcode("user", function(name, twitterUsername) { … });

  // Universal Shortcodes (Adds to Liquid, Nunjucks, JavaScript, Handlebars)
  eleventyConfig.addShortcode("user", function(name, twitterUsername) {
    return `<div class="user">
<div class="user_name">${name}</div>
<div class="user_twitter">@${twitterUsername}</div>
</div>`;
  });
};

Nunjucks Template Usage

{% user "Zach Leatherman", "zachleat" %}

Outputs

<div class="user">
	<div class="user_name">Zach Leatherman</div>
	<div class="user_twitter">@zachleat</div>
	>
</div>

Paired Shortcode

module.exports = function(eleventyConfig) {
  // Nunjucks Shortcode
  eleventyConfig.addPairedNunjucksShortcode("user", function(bioContent, name, twitterUsername) { … });

  // Universal Shortcodes (Adds to Liquid, Nunjucks, Handlebars)
  eleventyConfig.addPairedShortcode("user", function(bioContent, name, twitterUsername) {
    return `<div class="user">
<div class="user_name">${name}</div>
<div class="user_twitter">@${twitterUsername}</div>
<div class="user_bio">${bioContent}</div>
</div>`;
  });
};

Nunjucks Usage

Note that you can put any Nunjucks tags or content inside the {% user %} shortcode! Yes, even other shortcodes!

{% user "Zach Leatherman", "zachleat" %}
  Zach likes to take long walks on Nebraska beaches.
{% enduser %}

Outputs

<div class="user">
	<div class="user_name">Zach Leatherman</div>
	<div class="user_twitter">@zachleat</div>
	<div class="user_bio">Zach likes to take long walks on Nebraska beaches.</div>
</div>

Shortcode Named Argument Syntax (Nunjucks-only)

Creates a single argument object to pass to the shortcode.

module.exports = function (eleventyConfig) {
	// Nunjucks Shortcode
	eleventyConfig.addNunjucksShortcode("user", function (user) {
		return `<div class="user">
<div class="user_name">${user.name}</div>
${user.twitter ? `<div class="user_twitter">@${user.twitter}</div>` : ""}
</div>`;
	});
};

Nunjucks Usage

The order of the arguments doesn’t matter.

{% user name="Zach Leatherman", twitter="zachleat" %}
{% user twitter="zachleat", name="Zach Leatherman" %}

Outputs

<div class="user">
	<div class="user_name">Zach Leatherman</div>
	<div class="user_twitter">@zachleat</div>
</div>

Nunjucks Usage

Importantly, this syntax means that any of the arguments can be optional (without having to pass in a bunch of null, null, null to maintain order).

{% user name="Zach Leatherman" %}

Outputs

<div class="user">
	<div class="user_name">Zach Leatherman</div>
</div>

Asynchronous Shortcodes

Note that the configuration methods here to add asynchronous shortcodes are different than their synchronous counterparts. This is just another gentle reminder here that these API methods are pretty verbose and it’s probably easier to add a Universal shortcode instead.

module.exports = function (eleventyConfig) {
	eleventyConfig.addNunjucksAsyncShortcode(
		"user",
		async function (name, twitterUsername) {
			return await fetchAThing();
		}
	);

	eleventyConfig.addPairedNunjucksAsyncShortcode(
		"user2",
		async function (content, name, twitterUsername) {
			return await fetchAThing();
		}
	);
};

Nunjucks Usage

This is identical to the synchronous Nunjucks usage.

{% user "Zach Leatherman", "zachleat" %}

{% user2 "Zach Leatherman", "zachleat" %}
  Zach likes to take long walks on Nebraska beaches.
{% enduser2 %}

Warning: The set Tag Does Not Work With Async Content

Nunjucks’ {% set %} tag does not work to capture asynchronous content (e.g. asynchronous shortcodes).

Added in v1.0.0Starting in Eleventy v1.0.0, Eleventy provides a {% setAsync %} tag to work around this limitation. Notably and contrary to set, setAsync’s first argument is a string.

{% setAsync "myVariableName" %}
{% myAsyncShortcode %}
{% endsetAsync %}

<!-- Now use the variable -->
{{ myVariableName }}

Access to page data values

If you aren’t using an arrow function, Nunjucks Shortcodes (and Handlebars, Liquid, and 11ty.js JavaScript Functions) will have access to Eleventy page data values without needing to pass them in as arguments.

module.exports = function (eleventyConfig) {
	eleventyConfig.addNunjucksShortcode("myShortcode", function () {
		// Available in 0.11.0 and above
		console.log(this.page);

		// For example:
		console.log(this.page.url);
		console.log(this.page.inputPath);
		console.log(this.page.fileSlug);
	});
};

Generic Global Added in v1.0.0

Nunjucks provides a custom way to add globals to templates. These can be any arbitrary JavaScript: functions, variables, etc. Note that this is not async-friendly (Nunjucks does not support await inside of templates).

module.exports = function (eleventyConfig) {
	eleventyConfig.addNunjucksGlobal("fortythree", 43);
};

{{ fortythree }}

module.exports = function (eleventyConfig) {
	eleventyConfig.addNunjucksGlobal("fortytwo", function () {
		return 42;
	});
};

{{ fortytwo() }}

Read more on the Nunjucks documentation or relevant discussion on Eleventy Issue #1060.

Other pages in Template Languages:

• HTML
• Markdown
  • MDX
• WebC
• JavaScript
  • JSX
  • TypeScript
• Nunjucks
• Liquid
• Handlebars
• Mustache
• EJS
• HAML
• Pug
• Custom

Related Docs

• Template Custom Tags
• Template Filters
• Template Shortcodes