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Eleventy Documentation

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Fetch Jump to heading

Fetch network resources and cache them so you don’t bombard your API (or other resources). Do this at configurable intervals—not with every build! Once per minute, or once per hour, once per day, or however often you like!

With the added benefit that if one successful request completes, you can now work offline!

This plugin can save any kind of asset—JSON, HTML, images, videos, etc.

This plugin was formerly known as @11ty/eleventy-cache-assets.

Installation Jump to heading 

npm install @11ty/eleventy-fetch

Formerly known as @11ty/eleventy-cache-assets.

Important Security and Privacy Notice

This plugin caches complete network responses. Unless you’re willing to perform a full review of everything this plugin caches to disk for privacy and security exposure, it is strongly recommended that you add the .cache folder to your .gitignore file so that network responses aren’t checked in to your git repository.

Are you 100% sure that private e-mail addresses aren’t being returned from a cached API? I’m guessing no—add .cache to your .gitignore file. Right now. Do it.

Usage Jump to heading

Cache a JSON file from an API Jump to heading

Consider the following example, perhaps in an Eleventy Global Data File.

const EleventyFetch = require("@11ty/eleventy-fetch");

module.exports = async function() {
  let url = "https://api.github.com/repos/11ty/eleventy";

  /* This returns a promise */
  return EleventyFetch(url, {
    duration: "1d", // save for 1 day
    type: "json"    // we’ll parse JSON for you
  });
};

Options Jump to heading

Verbose Output Jump to heading

New in Fetch 3.0 Option to log requested remote URLs to the console.

Change the Cache Duration Jump to heading

After this amount of time has passed, we’ll make a new network request to the URL to fetch fresh data. Use duration: "*" to never fetch new data. The duration option also currently supports the following shorthand values:

Type Jump to heading

Cache Directory Jump to heading

The directory option let’s you change where the cache is stored. It is strongly recommended that you add this folder to your .gitignore file.

Read the Important Security and Privacy Notice.
const EleventyFetch = require("@11ty/eleventy-fetch");

EleventyFetch("https://…", {
	directory: ".cache"
});

If you want to use this utility inside of a Netlify Function (or AWS Lambda), use a writeable location (/tmp/) like directory: "/tmp/.cache/". You can also use dryRun: true to skip writing to the file system.

Remove URL query params from Cache Identifier Jump to heading

(Version 2.0.3 and newer) If your fetched URL contains some query parameters that aren’t relevant to the identifier used in the cache, remove them using the removeUrlQueryParams option. This is useful if an API adds extra junk to your request URLs.

const EleventyFetch = require("@11ty/eleventy-fetch");

EleventyFetch("https://www.zachleat.com/img/avatar-2017-big.png?Get=rid&of=these", {
  removeUrlQueryParams: true
});

Note that query params are removed before—and are relevant to how—the hash key is calculated.

What happens when a request fails? Jump to heading

  1. If this is the first ever request to this URL (no entry exists in your cache folder), it will fail. Use a try/catch if you’d like to handle this gracefully.
  2. If a failure happens and a cache entry already exists (even if it’s expired), it will use the cached entry.
  3. If you prefer the build to fail when your API requests fail, leave out the try catch and let the error throw without handling it!
const EleventyFetch = require("@11ty/eleventy-fetch");

module.exports = async function() {
	try {
    let url = "https://api.github.com/repos/11ty/eleventy";

		/* This returns a promise */
		return EleventyFetch(url, {
			duration: "1d",
			type: "json"
		});
	} catch(e) {
		return {
			// my failure fallback data
		}
	}
};

Running this on your Build Server Jump to heading

If you’re attempting to use this plugin on a service like Netlify and you are definitely not checking in your .cache folder to git, the .cache folder will be empty with every build and you’ll always get fresh data from new requests.

However, if you’d like to persist your .cache folder between Netlify builds you can use the netlify-plugin-cache package.

  1. npm install netlify-plugin-cache
  2. Add the following to your netlify.toml configuration file:
[[plugins]]
package = "netlify-plugin-cache"

  [plugins.inputs]
  paths = [ ".cache" ]

More Examples Jump to heading

Cache a Remote Image Jump to heading

This is what eleventy-img uses internally.

const EleventyFetch = require("@11ty/eleventy-fetch");

module.exports = async function() {
  let url = "https://www.zachleat.com/img/avatar-2017-big.png";
  let imageBuffer = await EleventyFetch(url, {
    duration: "1d",
    type: "buffer"
  });
  // Use imageBuffer as an input to the `sharp` plugin, for example

  // (Example truncated)
}

Fetch Google Fonts CSS Jump to heading

Also a good example of using fetchOptions to pass in a custom user agent. Full option list is available on the node-fetch documentation.

const EleventyFetch = require("@11ty/eleventy-fetch");

let url = "https://fonts.googleapis.com/css?family=Roboto+Mono:400&display=swap";
let fontCss = await EleventyFetch(url, {
	duration: "1d",
	type: "text",
	fetchOptions: {
		headers: {
			// lol
			"user-agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36"
		}
	}
});

Fetching GitHub Stars for a repo Jump to heading

Advanced Usage Jump to heading

Manually store your own data in the cache Jump to heading

You probably won’t need to do this. If you’d like to store data of your own choosing in the cache (some expensive thing, but perhaps not related to a network request), you may do so! Consider the following Global Data File:

const { AssetCache } = require("@11ty/eleventy-fetch");

module.exports = async function() {
  // Pass in your unique custom cache key
  // (normally this would be tied to your API URL)
  let asset = new AssetCache("zachleat_twitter_followers");

  // check if the cache is fresh within the last day
  if(asset.isCacheValid("1d")) {
    // return cached data.
    return asset.getCachedValue(); // a promise
  }

  // do some expensive operation here, this is simplified for brevity
  let fakeTwitterApiContents = { followerCount: 1000 };

  await asset.save(fakeTwitterApiContents, "json");

  return fakeTwitterApiContents;
};

Change Global Concurrency Jump to heading 

const EleventyFetch = require("@11ty/eleventy-fetch");
EleventyFetch.concurrency = 4; // default is 10

DEBUG mode Jump to heading 

DEBUG=EleventyCacheAssets* node your-node-script.js
DEBUG=EleventyCacheAssets* npx @11ty/eleventy

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