Navigator 3.0
plugin.name
The name property of a Plugin object is a read-only string that specifies the name of the plug-in. Each plug-in should have a name that uniquely identifies it.
The value of the name property can also be used as an index into the navigator.plugins[] array. You can use this fact to easily determine whether a particular named plug-in is installed in the current browser:
var sw_installed = (navigator.plugins["Shockwave"] != null);
Note that some plug-ins may support a configurable list of MIME types. Once you have determined that a desired plug-in is installed, you may also need to consult the Plugin.mimeTypes[] array to be sure that the plug-in can display the type of data you want it to.