Firebase Cloud Messaging (FCM) custom service worker

firebase-messaging-sw.js

self.addEventListener("push", (event) => {
    const notif = event.data.json().notification;
    event.waitUntil(self.registration.showNotification(notif.title, {
        body: notif.body,
        icon: notif.image, /* or "icon.png" */
        data: {
            url: notif.click_action
        }
    }))
})

self.addEventListener("notificationclick",(event) => {
    event.waitUntil(clients.openWindow(event.notification.data.url))
})