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Customizing 11ty Collections

Updated on: Mar 24, 2021 by Stephanie Eckles
🍿 2 min. read

Create randomized and other variations for your Eleventy collections.

Collections from Custom Data

If you have custom data that you don't need paginated but do need to customize the returned items, here's how to create it as a collection.

In this example, replace customData with the filename of your custom data.

eleventyConfig.addCollection("customDataCollection", (collection) => {
const allItems = collection.getAll()[0].data.customData;

// Filter or use another method to select the items you want
// for the collection
return allItems.filter((item) => {
// ...

randomizedPosts Collection

Create a randomized version of a tag collection.

As opposed to the random filters, a collection will persist throughout your site, whereas filters used on multiple pages will produce randomized results per page.

eleventyConfig.addCollection("randomizedPosts", function (collection) {
return (
// Change to the name of your tag
.sort(() => {
return 0.5 - Math.random();
// Optional limit, remove if unwanted
.slice(0, 3)

Collections Based on Frontmatter

Useful for when you may not want to create the collections by duplicating tags and instead use a custom frontmatter key.

eleventyConfig.addCollection("specialCollection", function (collection) {
return collection.getAll().filter((post) =>;
View more config samples