If a website visitor has an adware toolbar installed, it executes popups when the visitor comes to my page.
Is there a way to run Javascript on my page that will detect this activity and stop it? Or, is there a way to detect and redirect the user to a page with removal instructions?
Theoretically, yes.
It all depends on whether the toolbar is exposing a public variable that javascript can access. For example, MyToolbar for Chrome, could expose the object, mt then you can just do a
if ( typeof mt !== 'undefined' ) { // they have it installed.
You would need to research the toolbars, and find whether they expose these or not.
