Using ActiveX and Plug-Ins with JavaScript - Beginning JavaScript - page 473

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Figure 13-3

If the Flash plug-in is not installed, navigator.plugins[“Shockwave Flash”] will be undefined ,
which JavaScript considers to be false , thereby causing the else statement to execute. If Flash is installed,
navigator.plugins[“Shockwave Flash”] will return the Flash Plugin object, which JavaScript treats
as true , and the main if statement will execute.

The problem with this method of detection is that the name given to a plug-in may vary from operating
system to operating system. For example, the name of the Windows XP version of the plug-in may vary
from the name of the Mac version, which in turn may vary from the name of the Linux version. Some
plug-ins, such as RealPlayer, will not work reliably at all with this detection method, because the name
is not simply RealPlayer but something that contains the word “RealPlayer.”

An alternative method for determining whether a plug-in is installed is to loop through the plugins[]
array and check each name for certain keywords. If you fi nd them, you can assume that the control is
installed. For example, to check for QuickTime, you may use the following:

var pluginsLength = navigator.plugins.length;
for (var i = 0; i < pluginslength; plugInCounter++)
{
var name = navigator.plugins[i].name.toLowerCase();
if (name.indexOf(“quicktime”) > -1)
{
alert(“QuickTime is installed”);