Question

For some reason I’m having trouble trying to recognize the mousewheel event in Firefox. This is working in IE, Chrome, Safari, Opera but not FF. I am attaching an event listener on DOMMouseScroll, which should be recognized in FF.

Fiddle demo

$(document).unbind('mousewheel DOMMouseScroll').on('mousewheel DOMMouseScroll', function(e) {
    var evt = event || e || window.event;
    var delta = evt.detail < 0 || evt.wheelDelta > 0 ? 1 : -1;

    if (delta < 0) {
        // scroll down
    } else {
        // scroll up
    }
});

Answer 1

Your code generates an error in the console. The line:

var evt = event || e || window.event;

is incorrect; there’s no “event” variable in scope. You can just use “e” directly. The jQuery code will make sure your handler gets the event parameter as a parameter. Or:

$(document).unbind('mousewheel DOMMouseScroll').on('mousewheel DOMMouseScroll', function(evt) {
    var delta = evt.detail < 0 || evt.wheelDelta > 0 ? 1 : -1;

    if (delta < 0) {
        // scroll down
    } else {
        // scroll up
    }
});