Cache
Finds the Cache entry whose key is the request, returning a Promise that resolves to true if a matching Cache entry is found and deleted. If no Cache entry is found, the promise resolves to false . Takes both a request and its response and adds it to the given cache. Takes an array of URLs, retrieves them, and adds the resulting response objects to the given cache. Takes a URL, retrieves it and adds the resulting response object to the given cache. This is functionally equivalent to calling f