php code to detect browser plugins

How can I detect browser plugins with php like 开发者_StackOverflow社区this page does?

I want to detect flash player and silverlight to load the correct content (animation) in a webpage with php.

Thanks for the help.

PHP doesn't get information on the browser's plugins unless that plugin adds something to the user agent string (which is unusual). That page uses JavaScript to detect plugins, which is the most common way of implementing this sort of thing.