What links a click/tap position to select an object on screen?

What links a click/tap position to select an object on screen?

• It's so normal that a user's (double) click, or tap (and hold), on screen would trigger selecting an object located in the same position. I just wonder what layer of the software stack implements the link between a user's click/tap position to the selected object. Is it on Javascript, Browser, or OS? I feel like it should be the OS, but I am not sure. Experts please help me understand. It would be great if some implementation details can be shared.

• Answer:

  I have studied somewhere that there would be two potentiometers across the screen. Their intersection point would give out the pixel(s). This is as far as hardware configuration is concerned. But what is at that location i.e., the app or some other thing is something which the OS has to identify and delegate control to that app accordingly.