This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The add() method of the Cache interface takes a URL, retrieves it, and adds the resulting response object to the given cache. The add() method is functionally equivalent to the following:

fetch(url).then(function(response) {
  if (!response.ok) {
    throw new TypeError('bad response status');
  return cache.put(url, response);

For more complex operations, you'll need to use Cache.put() directly.

Note: add() will overwrite any key/value pair previously stored in the cache that matches the request.

Note: Initial Cache implementations (in both Blink and Gecko) resolve Cache.add, Cache.addAll, and Cache.put promises when the response body is fully written to storage.  More recent spec versions state that the browser can resolve the promise as soon as the entry is recorded in the database even if the response body is still streaming in.


cache.add(request).then(function() {
  // request has been added to the cache


The request you want to add to the cache. This can be a  Request object or a URL.

Return value

A Promise that resolves with void.


Exception Happens when

The URL scheme is not http or https.

The Response status is not in the 200 range (i.e., not a successful response.) This occurs if the request does not return successfully, but also if the request is a cross-origin no-cors request (in which case the reported status is always 0.)


This code block waits for an InstallEvent to fire, then calls waitUntil() to handle the install process for the app. This consists of calling to create a new cache, then using Cache.add to add an asset to it.

this.addEventListener('install', function(event) {
  event.waitUntil('v1').then(function(cache) {
      return cache.add('/sw-test/index.html');


Specification Status Comment
Service Workers
The definition of 'Cache' in that specification.
Working Draft Initial definition.

Browser compatibility

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 46 (Yes) (Yes)[1] No support 33 No support
Require HTTPS 46 (Yes) (Yes)[1] ? 33 ?
TypeError if request is not successful (Yes) ? 47.0 (47.0)[1] (Yes) (Yes) (Yes)
Feature Android Webview Chrome for Android Firefox Mobile (Gecko) Firefox OS IE Mobile Opera Mobile Safari Mobile
Basic support 46 46 (Yes) ? No support 33 No support
Require HTTPS 46 46 (Yes) ? ? 33 ?
TypeError if request is not successful (Yes) (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

[1] Service workers (and Push) have been disabled in the Firefox 45 & 52 Extended Support Releases (ESR.)

See also

Document Tags and Contributors

 Contributors to this page: erikadoyle, jpmedley, tomayac, chrisdavidmills, bkelly, kscarfone
 Last updated by: erikadoyle,