capturing f5 keypress event in javascript using window.event.keyCode in [removed] event is always 0 and not 116

Question

i am creating an MVC application.There was a neccessitity to make a variable in a session to null upon closing of the application (i.e. window/tab) but not upon refreshing t

Answer 1

document.onkeydown = disableF5;
document.onkeypress = disableF5
document.onkeyup = disableF5;    
function disableF5(e) { if ((e.which || e.keyCode) == 116) e.preventDefault(); };