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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