activate.js

self.addEventListener('activate', (event) => {
    let cacheWhitelist = ['products-v2'] // products-v2 is the name of the new cache

    event.waitUntil(
        caches.keys().then (cacheNames => {
            return Promise.all(
                cacheNames.map( cacheName => {
                    /* Deleting all the caches except the ones that are in cacheWhitelist array */
                    if (cacheWhitelist.indexOf(cacheName) === -1) { 
                        return caches.delete(cacheName)
                    }
                })
            )
        })
    )
})