Detect if browser has more then 1 tab/window open
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So i am developing a quiz web application. And i wanted to add a setting that the administrator of the quiz could set that would make it so the user could only have 1 window/tab open while the quiz is being taken. 

The reason for this is to make it so they cant goto like google and google the answer while the quiz window/tab is open. Of course they could always open a different browser and do it that way, but still thought it would be a nice feature to have for them to enable.

Now i dont know if this would fall under a security sandbox violation (and thus not be available at all) but since i only want to detect if another tab or window is open and not get actual information about the tab/window i am hoping that this is someway possible using javascript.