if ('serviceWorker' in navigator) {
caches.keys().then(function(cacheNames) {
cacheNames.forEach(function(cacheName) {
caches.delete(cacheName);
});
});
}self.addEventListener('activate', function(event) {
event.waitUntil(
caches.keys().then(function(cacheNames) {
return Promise.all(
cacheNames.filter(function(cacheName) {
// Return true if you want to remove this cache,
// but remember that caches are shared across
// the whole origin
}).map(function(cacheName) {
return caches.delete(cacheName);
})
);
})
);
});