Progressive Web Application Development by Example

The time-to-live invalidation strategy

Like the maxItems strategy, the updateStaleEntries strategy opens a reference to the named cache and gets a list of the cached requests. This time, individual requests must be retrieved from the cache.

This requires calling the cache's match method by passing a request object (key). This will return the stored response with a date header. This is added when the item is added to the cache and can be used to determine if the response is stale:

updateStaleEntries(rule) { 
 
    self.caches.open(rule.cacheName) 
        .then(cache => { 
 
            cache.keys().then(keys => { 
 
                keys.forEach((request, index, array) => { 
 
                    cache.match(request).then(response => { 
 
                        let date = new  Date(response.headers.get("date")), current = new Date(Date.now()); ...