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
    JavaScript Speech Recognition

    Speech recognition software is becoming more and more important; it started (for me) with Siri on iOS, then Amazon's Echo, then my new Apple TV, and so on.  Speech recognition is so useful for not just us tech superstars but for people who either want to work "hands...

  • By
    Google Extension Effect with CSS or jQuery or MooTools JavaScript

    Both of the two great browser vendors, Google and Mozilla, have Extensions pages that utilize simple but classy animation effects to enhance the page. One of the extensions used by Google is a basic margin-top animation to switch between two panes: a graphic pane...

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.

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