Install a service handler for URI scheme from webpage

For Chrome (13+), Firefox (3.0+) and Opera (11.60+) it is possible to register web application as service handler for custom URI scheme using JavaScript API:

window.navigator.registerProtocolHandler(protocol, uri, title);

• protocol is the protocol the site wishes to handle, specified as a string.
• uri is the URI to the handler as a string. You can include "%s" to indicate where to insert the escaped URI of the document to be handled.
• title is the title of the handler presented to the user as a string.

Specifically for Chrome there is a limitation that does not allow to use custom schemes that don't start with web+ prefix (except standard ones: mailto, mms, nntp, rtsp and webcal). So if you want to register your web app as service handler as GMail do, you should write something like this:

navigator.registerProtocolHandler("mailto", "https://www.example.com/?uri=%s", "Example Mail");

or

navigator.registerProtocolHandler("web+myscheme", "https://www.example.com/?uri=%s", "My Cool App");

Pay attention at URI pattern, it have to contain %s which will be replaced with actual URI of the link user clicks. For example:

<a href="web+myscheme:some+data">Open in "My Cool App"</a>

will trigger GET request to http://www.example.com/?uri=web%2Bmyscheme%3Asome%20data

Here are some useful links:

• Standard http://www.whatwg.org/specs/web-apps/current-work/#custom-handlers
• MDN https://developer.mozilla.org/en-US/docs/DOM/navigator.registerProtocolHandler
• HTML5ROCKS http://updates.html5rocks.com/2011/06/Registering-a-custom-protocol-handler