javascript

Chapter 8: The Browser Object Model
The registerContentHandler() method accepts three arguments: the MIME type to handle, the URL
of the page that can handle that mime type, and the name of the application. For instance, to register a
site as a handler of RSS feeds, you can use the following code:
navigator.registerContentHandler(“application/rss+xml”,
“http://www.somereader.com?feed=%s”, “Some Reader”);
The first argument is the MIME type for RSS feeds. The second argument is the URL that should receive
the RSS - feed URL. In this second argument, the %s represents the URL of the RSS feed, which the
browser inserts automatically. The next time a request is made for an RSS feed, the browser will navigate
to the URL specified and the web application can handle the request in the appropriate way.
Firefox 2 allows only three MIME types to be used in registerContentHandler() :
“ application/rss+xml ” , “ application/atom+xml ” , and “ application/vnd.
mozilla.maybe.feed ” . All three do the same thing: register a handler for all RSS
and Atom feeds.
A similar call can be made for protocols by using registerProtocolHandler() , which also accepts
three arguments: the protocol to handle (i.e., “ mailto ” or “ ftp “ ), the URL of the page that handles the
protocol, and the name of the application. For example, to register a web application as the default mail
client, you can use the following:
navigator.registerProtocolHandler(“mailto”,
“http://www.somemailclient.com?cmd=%s”, “Some Mail Client”);
In this example, a handler is registered for the mailto protocol, which will now point to a web - based
e-mail client. Once again, the second argument is the URL that should handle the request, and %s
represents the original request.
In Firefox 2, registerProtocolHandler() is implemented but does not work.
The screen Object
The screen object (also a property of window ) is one of the few JavaScript objects that have little to no
programmatic use; it is used purely as an indication of client capabilities. This object provides
information about the client ’ s display outside the browser window, including information such as pixel
width and height. Each browser provides different properties on the screen object. The following table
indicates the properties and which browsers support them.
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