How can I check whether an extension(BHO) is installed in IE 6/7/8?

How can I check whether开发者_StackOverflow社区 an extension(BHO) is installed in IE 6/7/8, with javascript code in a webpage?

You need to include an ActiveX control in your extension.

1. This should be a separate COM object from your BHO.
2. Make sure to SiteLock the control to your domain.

Then, on your website, you can just try to create that control:

var foo;
try {
    foo = new ActiveXObject("your.control");
} catch (e) {
    foo = null;
}

if (foo == null) {
    // Your package not installed.
}