Web Push Notifications: Timely, Relevant, and Precise

作者：Joseph Medley

If you ask a room of developers what mobile device features are missing from the web, push notifications are always high on the list.

Web push notifications allow users to opt-in to timely updates from sites they love and allow you to effectively re-engage them with customized, relevant content.

The Push API and Notification API open a whole new set of possibilities for you to re-engage with your users.

Are service workers involved?

Yes. Push is based on service workers because service workers operate in the background. This means the only time code is run for a push notification (in other words, the only time the battery is used) is when the user interacts with a notification by clicking it or closing it. If you're not familiar with them, check out theservice worker introduction. We will use service worker code in later sections when we show you how to implement pushes and notifications.

Two technologies

Push and notification use different, but complementary, APIs:pushis invoked when a server supplies information to a service worker; anotificationis the action of a service worker or web page script showing information to a user.

A little notification anatomy

In the next section we're going to throw a bunch of pictures at you, but we promised code. So, here it is. With a service worker registration you callshowNotificationon a registration object.

serviceWorkerRegistration.showNotification(title, options);

Thetitleargument appears as a heading in the notification. Theoptionsargument is an object literal that sets the other properties of a notification. A typical options object looks something like this:

{
  "body": "Did you make a $1,000,000 purchase at Dr. Evil...",
  "icon": "images/ccard.png",
  "vibrate": [200, 100, 200, 100, 200, 100, 400],
  "tag": "request",
  "actions": [
    { "action": "yes", "title": "Yes", "icon": "images/yes.png" },
    { "action": "no", "title": "No", "icon": "images/no.png" }
  ]
}

This code produces a notification like the one in the image. It generally provides the same capabilities as a native application. Before diving into the specifics of implementing those capabilities, I'll show you how to use those capabilities effectively. We'll go on to describe the mechanics of implementing push notifications, including handling permissions and subscriptions, sending messages, and responding to them.

How can I try it?

There are several ways you can play with the features before you completely understand how they work, or have to implement them. First, check outour own sample. Also available are Peter Beverloo'sNotification Generatorand Mozilla'sPush Payload Demo.

Note:Unless you're using localhost, the Push API requires HTTPS.