Protocol Handlers

What's a Protocol exactly?

A protocol (also known as a URL scheme) is the first part of a URL. The most common examples are http: and https: which are used for web pages. You might also recognize mailto: which opens your email client when followed by an email address, or tel: which precedes a phone number and typically prompts a call.

Protocol handlers in PWAs

As it turns out, PWAs can register themselves as protocol handlers. When a user opens a URL that begins with one of the protocols you’ve registered, your PWA can appear as an available option to handle it. There are two ways to do this:

1. Use navigator.registerProtocolHandler() in your client-side JavaScript code
2. Set the protocol_handlers property in your app manifest

In both scenarios, the handler URL must contain the placeholder %s. At runtime, this placeholder is replaced with the actual URL passed to your application.

Code

Links & Documentation

• Protocol Handlers Manifest Property on Chrome for developers
• navigator.registerProtocolHandler() on MDN
• Protocol Handlers Manifest Property on MDN