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Harit Himanshu
Harit Himanshu

Posted on

What does event.waitUntil do in service worker and why is it needed?

MDN suggests that you do the following to create and populate service worker cache:

this.addEventListener('install', function(event) {
  event.waitUntil('v1').then(function(cache) {
      return cache.addAll([
        ... etc ...

I do not understand that code. The waitUntil method is documented too, and it seems the code above is…

Top comments (1)

sargalias profile image
Spyros Argalias

According to the MDN docs on ExtendableEvent.waitUntil() it prevents the service worker from terminating until the work inside the function is done. This is because the work inside the function is asynchronous, it could potentially take many seconds to complete.

Essentially it just waits for the promise to be fulfilled.