Detect WEBP Support with JavaScript

By  on  

Image optimization is a huge part of improving front-end performance.  We've traditionally used JPG/JPEG, GIF, and PNG images but Google and the Chrome team developed the WEBP format which crunches file size and optimizes rendering.  If you go to a site like GIPHY in Chrome you'll be served a WEBP, but if you go to the same page in Firefox you'll be served a GIF.  Since GIPHY lazy loads its images, GIPHY has the opportunity to use WEBP feature detection with JavaScript.

Googler and Service Worker pioneer Jake Archibald recently tweeted a snippet showing how you can use a service worker to detect WEBP support:

async function supportsWebp() {
  if (!self.createImageBitmap) return false;
  
  const webpData = 'data:image/webp;base64,UklGRh4AAABXRUJQVlA4TBEAAAAvAAAAAAfQ//73v/+BiOh/AAA=';
  const blob = await fetch(webpData).then(r => r.blob());
  return createImageBitmap(blob).then(() => true, () => false);
}

(async () => {
  if(await supportsWebp()) {
    console.log('does support');
  }
  else {
    console.log('does not support');
  }
})();

Jake fetches a valid WEBP data URI to determine if the browser supports WEBP -- genius!  His script also uses async / await to handle promises which I will be covering soon on this blog.  Note that this code works outside a service worker, so you can use it anywhere within your own projects.

If your site is heavy on imagery, consider formatting your images with WEBP; Chrome's market share is so large that it will definitely be worth it.  If you like small tips like this, be sure to follow Jake on Twitter!

Recent Features

Incredible Demos

  • By
    MooTools, Mario, and Portal

    I'm a big fan of video games. I don't get much time to play them but I'll put down the MacBook Pro long enough to get a few games in. One of my favorites is Portal. For those who don't know, what's...

  • By
    Chris Coyierâs Favorite CodePen Demos IV

    Did you know you can triple-heart things on CodePen? We’ve had that little not-so-hidden feature forever. You can click that little heart button on any Pen (or Project, Collection, or Post) on CodePen to show the creator a little love, but you can click it again...

Discussion

  1. Nice snippet there!

    You can also utilise picture to define a series of image types and let the browser decide what to load.

  2. It doesn’t correctly detect WebP on Firefox though! :(

  3. Alex

    It is funny to use .createImageBitmap for WebP detection, method that Safari, Edge and IE — main targets for detection — doesn’t support.

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!