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

  • By
    5 HTML5 APIs You Didn’t Know Existed

    When you say or read "HTML5", you half expect exotic dancers and unicorns to walk into the room to the tune of "I'm Sexy and I Know It."  Can you blame us though?  We watched the fundamental APIs stagnate for so long that a basic feature...

  • By
    Animated 3D Flipping Menu with CSS

    CSS animations aren't just for basic fades or sliding elements anymore -- CSS animations are capable of much more.  I've showed you how you can create an exploding logo (applied with JavaScript, but all animation is CSS), an animated Photo Stack, a sweet...

Incredible Demos

  • By
    WebKit Marquee CSS:  Bringin’ Sexy Back

    We all joke about the days of Web yesteryear.  You remember them:  stupid animated GIFs (flames and "coming soon" images, most notably), lame counters, guestbooks, applets, etc.  Another "feature" we thought we had gotten rid of was the marquee.  The marquee was a rudimentary, javascript-like...

  • By
    Create a Spinning, Zooming Effect with CSS3

    In case you weren't aware, CSS animations are awesome.  They're smooth, less taxing than JavaScript, and are the future of node animation within browsers.  Dojo's mobile solution, dojox.mobile, uses CSS animations instead of JavaScript to lighten the application's JavaScript footprint.  One of my favorite effects...

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!