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

I agree with meo's solution, but I will add some modifications.

when we use document.onkeydown = fkey; for example and in the page we have another method affected to the document.onkeydown then the browser will detect only the last event. However when we use : jQuery(document).on("keydown",fkey); even if we have another function to handle the keydown event, all the functions will be triggered.

see the next example to more understand:

var wasPressed = false;
document.onkeydown = f1;
document.onkeydown = f2;

jQuery(document).on("keydown",f3); 
jQuery(document).on("keydown",f4); 
function f1(e){
e = e || window.event;
if( wasPressed ) return; 

        if (e.keyCode == 116) {
             alert("f5 pressed");
            wasPressed = true;
        }else {
            alert("Window closed");
        }
}
function f2(){
    alert('f2');
}
function f3(){
    alert('f3');
}
function f4(){
    alert('f4');
}

what will be shown here: only 3 alerts: f2,f3 and f4. and the f1 function isn't triggred in this example.