window.confirm在FireFox中不起作用

Question

Background: The goal is to keep a user from going back a page using the backspace. I've created code to disable the the key, except for a few input fields. But if they do, in fact, want to go back, I'd like for the confirm dialog to ask them if they REALLY want to go back or not.

Problem: The following code works in IE and Chrome, but not FF. The confirm pops up but it still goes 'back' a page. This doesn't happen in IE/Chrome as the confirm dialog waits for user input.

Code:

<script type="text/javascript">

    $(document).unbind('keydown').bind('keydown', function (event) {
        var doPrevent = false;
        if (event.keyCode === 8) {
            var d = event.srcElement || event.target;
            if ((d.tagName.toUpperCase() === 'INPUT' && 
                 (
                     d.type.toUpperCase() === 'TEXT' ||
                     d.type.toUpperCase() === 'PASSWORD' || 
                     d.type.toUpperCase() === 'FILE' || 
                     d.type.toUpperCase() === 'SEARCH' || 
                     d.type.toUpperCase() === 'EMAIL' || 
                     d.type.toUpperCase() === 'NUMBER' || 
                     d.type.toUpperCase() === 'DATE' )
                 ) || 
                 d.tagName.toUpperCase() === 'TEXTAREA') {


  doPrevent = d.readOnly || d.disabled;
        }
        else {
            var r = window.confirm("Leaving the page can cause data to be lost.  Are you sure?");
            if (!r) {
                doPrevent = true;
            }  
        }
    }

    if (doPrevent) {
        event.preventDefault();
        //event.stopPropagation(); 
    }
});

</script>

Answer 1

This fixed it and worked in each browser (Safari too):

   window.addEventListener("beforeunload", function (e) {

    var confirmationMessage = "Leaving the page can cause data to be lost.  Are you sure?";

    e.returnValue = confirmationMessage;     // Gecko and Trident
    return confirmationMessage;              // Gecko and WebKit

});