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JavaScriptNew in v0.7.0

Template Languages:

Eleventy Short NameFile ExtensionNPM Package
11ty.js.11ty.jsN/A

Eleventy supports many different types of JavaScript content that will be parsed as Eleventy templates:

Raw Values

Raw values will not have access to Data or JavaScript Template Functions. Use a function that returns a value instead.

String

Syntax JavaScript
module.exports = "<p>Zach</p>";

Or template literals:

Syntax JavaScript
module.exports = `<p>These can
span
multiple
lines!</p>`
;

Buffer

Some templating libraries return Buffers (e.g. viperHTML).

Syntax JavaScript
module.exports = Buffer.from("<p>Zách</p>");

Promise

Syntax JavaScript
module.exports = new Promise((resolve, reject) => {
setTimeout(function() {
resolve("<p>Zach</p>");
}, 1000);
});

Function

Can return any raw value (e.g. String, Buffer, Promise). Use template literals to embed data values without having to concatenate strings!

Syntax JavaScript
module.exports = function(data) {
return `<p>${data.name}</p>`;
};

De-structuring syntax is a little bit easier to read:

Syntax JavaScript
module.exports = function({name}) {
return `<p>${name}</p>`;
};

Maybe you like arrow functions:

Syntax JavaScript
module.exports = ({name}) => `<p>${name}</p>`;

async functions work too:

Syntax JavaScript
const getAnAsyncThing = require("./lib/asyncThing");

module.exports = async function(data) {
return `<p>${await getAnAsyncThing()}</p>`;
};

Classes

Eleventy looks for classes that have a render method and uses render to return the content of the template. render methods can be async.

render can return any raw value (e.g. String, Buffer, Promise).

Syntax JavaScript
class Test {
// or `async render({name}) {`
render({name}) {
return `<p>${name}</p>`;
}
}

module.exports = Test;

Optional data Method

YAML Front Matter is not supported in JavaScript template types. Use data methods instead!

This data acts as Front Matter for the template and similarly to Front Matter will take precedence over all other data in the data cascade. The data method can be asynchronous async data() or it can be a getter get data().

Syntax JavaScript
class Test {
// or `async data() {`
// or `get data() {`
data() {
return {
name: "Ted"
};
}

render({name}) {
// will always be "Ted"
return `<p>${name}</p>`;
}
}

module.exports = Test;

The permalink data key will work here. Permalinks can be a raw value (e.g. String, Buffer, Promise) or a Function that returns any raw value.

Syntax JavaScript
class Test {
data() {
return {
// Writes to "/my-permalink/index.html"
permalink: "/my-permalink/"
};
}

render(data) { /* … */ }
}

module.exports = Test;

Permalink Functions can return any raw value (e.g. String, Buffer, Promise).

Syntax JavaScript
class Test {
data() {
return {
key: "hello",
// Writes to "/my-permalink/hello/index.html"
permalink: data => `/my-permalink/${data.key}/`
};
}

render(data) { /* … */ }
}

module.exports = Test;

Universal filters, shortcodes, and other JavaScript Template Functions work here and are exposed on this. Read more about Eleventy provided Universal Filters.

Syntax JavaScript
class Test {
data() {
return {
title: "This is my blog post title",
// Writes to "/this-is-my-blog-post-title/index.html"
permalink: function(data) {
return `/${this.slug(data.title)}/`;
}
};
}

render(data) { /* … */ }
}

module.exports = Test;

Markdown and JavaScript

Yes, you can use JavaScript as your preprocessor language for Markdown. Read more about templateEngineOverride.

Syntax JavaScript and Markdown
class Test {
data() {
return {
myName: "Zach",
templateEngineOverride: "11ty.js,md"
};
}

render(data) {
return `# This is ${data.myName}`;
}
}

module.exports = Test;
While templateEngineOverride: 11ty.js,md works to add markdown support, the special behavior of JavaScript templates does not allow other template engines to be supported here (e.g. templateEngineOverride: njk,md). This will be mitigated with Enhancement Request Issue #148.

JavaScript Template Functions

A JavaScript Template Function allows you to extend your JavaScript templates with extra functionality. If you add any Universal Filters or Shortcodes, they will be exposed as JavaScript Template Functions.

Filename .eleventy.js
module.exports = function(eleventyConfig) {
eleventyConfig.addJavaScriptFunction("myFunction", function(a, b) {});
};

Usage

Filename js-fn-example.11ty.js
module.exports = function(data) {
return `<h1>${this.myFunction(data.a, data.b)}</h1>`;
};

Relationship to Filters and Shortcodes

Any universal filters or shortcodes will also be available as as JavaScript Template Functions.

Filename .eleventy.js
module.exports = function(eleventyConfig) {
// Universal filters (Adds to Liquid, Nunjucks, 11ty.js, and Handlebars)
eleventyConfig.addFilter("myFilter", function(myVariable) {});

// Universal Shortcodes (Adds to Liquid, Nunjucks, 11ty.js, Handlebars)
eleventyConfig.addShortcode("user", function(firstName, lastName) {});

// Universal Paired Shortcodes (Adds to Liquid, Nunjucks, 11ty.js, Handlebars)
eleventyConfig.addPairedShortcode("pairedUser", function(content, firstName, lastName) {});
};

Usage

Filename universal-examples.11ty.js
module.exports = function(data) {
return `
<h1>${this.myFilter(data.myVar)}</h1>
<p>${this.user(data.firstName, data.lastName)}</p>
<p>${this.pairedUser(`Here is some more content`, data.firstName, data.lastName)}</p>
`;
};

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