Customizing 11ty Collections

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) => {
    // ...
  });
});

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

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) => post.data.customKey);
});