window.onbeforeinstallprompt

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.

Syntax

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

Example

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

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

Specifications

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

See Also

• BeforeInstallPromptEvent.prompt
• BeforeInstallPromptEvent