[ACCEPTED]-Firefox 4 onBeforeUnload custom message-firefox4

Accepted answer
Score: 52

From MDN:

Note that in Firefox 4 and later the 8 returned string is not displayed to the 7 user. See Bug 588292.

This "Bug" is actually 6 a (imho questionable) feature.. so there's 5 no way to display the message in Firefox 4 4. If you think it should be changed, comment 3 on that bug so the Firefox developers will 2 know that people actually want to be able 1 to show a custom string.

Score: 32

Addition to the above Answer, I have improved 2 the workaround.

I have used jquery here. you 1 can use default javascript funciton as well.

$(window).bind('beforeunload', function() {
    if(/Firefox[\/\s](\d+)/.test(navigator.userAgent) && new Number(RegExp.$1) >= 4) {
        if(confirm("Are you Sure do you want to leave?")) {
        } else {
            window.setTimeout(function() {
            }, 1);
    } else {
        return "Are you Sure do you want to leave?";

Tested and working in firefox 11 as well. :)

Score: 3

My workaround is to show alert in onbeforeunload:

window.onbeforeunload=function() {
    if ( /Firefox[\/\s](\d+)/.test(navigator.userAgent) && new Number(RegExp.$1) >= 4) {
        alert("Blah blah. You have to confirm you are leaving this page in the next dialogue.");
    return "Blah blah."; 

(It 2 shows two dialogues in Firefox, one dialogue 1 elsewhere.)

Score: 1

Try implementing it with a confirm message,

   return confirm("Are you sure??");

of 4 course when the user confirms then the FF4 3 message is shown, so you maybe better display 2 this once per site on login/visit. A cookie 1 should do the trick.

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