The pageY property of the Event object controls the vertical (y-coordinate) positioning.
<html> <head> <title>Example of the event.pageY property</title> </head> <body> <script language = "JavaScript"> <!-- function handle(evnt){ alert("The Y coordinate of where the click event occurred is: " + evnt.pageY); return true; } window.onclick = handle; --> </script> Click in the web browser. </body> </html>