Check the mouse position in the screen

I have an iFrame with custom website page loaded into it. I am trying to find a way to get the word or text the mouse was hold down over it on that page using JS. To make it more clear, when the mouse was hold down on a specific word on the web page I want to do some actions in JS.

How can I do this check? I dont' have control over the web page content, I may load this StackOverFlow Question in the iFrame and if the user clicked on this bold word I want to do some actions in JS.

An开发者_如何学运维y idea?

You won't be able to access the contents of external iframes for security reasons (this includes setting event handlers). This response explains it further.