We use caches.match(event.request) in the service worker to do "Cache only strategy". I noticed that we also return cache.match('someURL') right after then of caches.open("cache-name") promises. This is quite confusing.

What is the difference between caches.match(event.request) and cache.match('someURL'). What is the use case for each of it?

Example cases:

Caches.match

self.addEventListener('fetch', function(event) {
  event.respondWith(caches.match(event.request)); 
});

Cache.match

self.addEventListener('fetch', function(event) {
  event.respondWith(
    caches.open('mysite-dynamic').then(function(cache) {
      return cache.match(event.request).then(function (response) {
        return response || fetch(event.request).then(function(response) {
          cache.put(event.request, response.clone());
          return response;
        });
      });
    })
  );
});

We use caches.match(event.request) in the service worker to do "Cache only strategy". I noticed that we also return cache.match('someURL') right after then of caches.open("cache-name") promises. This is quite confusing.

What is the difference between caches.match(event.request) and cache.match('someURL'). What is the use case for each of it?

Example cases:

Caches.match

self.addEventListener('fetch', function(event) {
  event.respondWith(caches.match(event.request)); 
});

Cache.match

self.addEventListener('fetch', function(event) {
  event.respondWith(
    caches.open('mysite-dynamic').then(function(cache) {
      return cache.match(event.request).then(function (response) {
        return response || fetch(event.request).then(function(response) {
          cache.put(event.request, response.clone());
          return response;
        });
      });
    })
  );
});

• javascript
• web-services
• caching

Share Improve this question Follow edited May 12, 2018 at 15:01 Rose G asked May 12, 2018 at 12:20 Rose GRose G 61811 gold badge99 silver badges1313 bronze badges 3

• what are caches and cache? – Thomas Commented May 12, 2018 at 12:22
• Without context for what caches and cache are, it's hard to say the exact difference. Still, they are two possibly unrelated objects. – VLAZ Commented May 12, 2018 at 12:23
• Sorry if my question is quite confusing. I added example cases which uses caches.match and cache.match in Service Worker – Rose G Commented May 12, 2018 at 15:02

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2 Answers 2

Sorted by: Reset to default 7

cache.match searches for an item in a specific cache, while caches.match searches all caches for a match.

I guess you didn't know that the word "caches" reffers to CacheStorage Basically caches or the cache storage stores all caches while cache is just a named cache inside the cache storage. Basically caches.match should get you the instance of the cache storage while cache.match gives you the instance of a specific cache.