The Window.onbeforeinstallprompt property is an event handler for processing a beforeinstallprompt, which is dispatched on mobile when a web manifest exists, but before a user is prompted to save a web site to a home screen.


window.addEventListener("beforeinstallprompt", function(event) { ... });
window.onbeforeinstallprompt = function(event) { ...};


The following example uses the beforeinstallprompt function to verify that it is an appropriate time to display an installation prompt to the user. If it is not, the event is redispatched.

var isTooSoon = true;
window.addEventListener("beforeinstallprompt", function(e) { 
  if (isTooSoon) {
    e.preventDefault(); // Prevents prompt display 
    // Prompt later instead: 
    setTimeout(function() { 
      isTooSoon = false; 
      e.prompt(); // Shows prompt 
    }, 10000); 
  // The event was re-dispatched in response to our request 
  // ... 

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support 45.0 [1] No support No support No support No support
Feature Android Android Webview Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile Chrome for Android
Basic support No support 45.0 [1] No support No support No support No support 45.0 [1]

[1] Behind the flagchrome://flags/#bypass-app-banner-engagement-checks


Specification Status Comment
Web App Manifest
The definition of 'Window.onbeforeinstallprompt' in that specification.
Working Draft Initial specification.

See Also

Document Tags and Contributors

 Contributors to this page: chrisdavidmills, jpmedley, teoli
 Last updated by: chrisdavidmills,