Navigator.registerProtocolHandler()

Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

The Navigator method registerProtocolHandler() lets websites register their ability to open or handle particular URL schemes (aka protocols).

For example, this API lets webmail sites open mailto: URLs, or VoIP sites open tel: URLs.

Syntax

registerProtocolHandler(scheme, url)
registerProtocolHandler(scheme, url, title)

Note: The version with the deprecated title argument is recommended for compatibility reasons (see parameter information below).

Parameters

scheme

A string containing the permitted scheme for the protocol that the site wishes to handle. For example, you can register to handle SMS text message links by passing the "sms" scheme.

url

A string containing the URL of the handler. This URL must include %s, as a placeholder that will be replaced with the escaped URL to be handled.

Note: The handler URL must use the https scheme. Older browsers also supported http.

title Deprecated

A human-readable title string for the handler. This will be displayed to the user, such as prompting "Allow this site to handle [scheme] links?" or listing registered handlers in the browser's settings.

Note: The title has been removed from the spec due to spoofing concerns. The title should still be set because some browsers still require it (see the compatibility table below). Browsers that support the updated spec most likely will be accept but ignore the title.

Return value

None (undefined).

Exceptions

SecurityError DOMException

The user agent blocked the registration. This might happen if:

  • The registered scheme (protocol) is invalid, such as a scheme the browser handles itself (https:, about:, etc.)
  • The handler URL's origin does not match the origin of the page calling this API.
  • The browser requires that this function is called from a secure context.
  • The browser requires that the handler's URL be over HTTPS.
SyntaxErrorDOMException

The %s placeholder is missing from the handler URL.

Permitted schemes

For security reasons, registerProtocolHandler() restricts which schemes can be registered.

A custom scheme may be registered as long as:

  • The custom scheme's name begins with web+
  • The custom scheme's name includes at least 1 letter after the web+ prefix
  • The custom scheme has only lowercase ASCII letters in its name.

For example, web+burger, as shown in the Example below.

Otherwise, the scheme must be one of the following:

  • bitcoin
  • ftp
  • ftps
  • geo
  • im
  • irc
  • ircs
  • magnet
  • mailto
  • matrix
  • mms
  • news
  • nntp
  • openpgp4fpr
  • sftp
  • sip
  • sms
  • smsto
  • ssh
  • tel
  • urn
  • webcal
  • wtai
  • xmpp

Examples

If your site is burgers.example.com, you can register a protocol handler for it to handle web+burger: links, like so:

navigator.registerProtocolHandler("web+burger",
                                  "https://burgers.example.com/?burger=%s",
                                  "Burger handler"); // last title arg included for compatibility

This creates a handler that lets web+burger: links send the user to your site, inserting the accessed burger URL into the %s placeholder.

This script must be run from the same origin as the handler URL (so any page at https://burgers.example.com), and the handler URL must be http or https.

The user will be notified that your code asked to register the protocol handler, so that they can decide whether or not to allow it. See the screenshot below for an example on google.co.uk:

A browser notification reads "Add Burger handler (www.google.co.uk) as an application for burger links?", and offers an "Add Application" button and a close to ignore the handler request.

Specifications

Specification
HTML Standard
# custom-handlers

Browser compatibility

BCD tables only load in the browser

See also