how can i prevent onbeforeunload from firing when a certain condition is met?

Question

i have a page on which i want to confirm if the user wants to leave. i have to confirm only when a certain condition is met so i wrote code like this

var bac         


        

Answer 1

Condition for back-end

var confirmExist = function (e) {
    return true;
}
window.onbeforeunload = confirmExist;
http get, post request
.then(function(r)) {
    window.onbeforeunload = null;
}