javascript scroll on stop

var scrollStop = function (callback) {
        // Make sure a valid callback was provided
        if (!callback || typeof callback !== 'function') return;
        // Setup scrolling variable
        var isScrolling;
        // Listen for scroll events
            window.addEventListener('scroll', function (event) {
                // Clear our timeout throughout the scroll
                window.clearTimeout(isScrolling);
                // Set a timeout to run after scrolling ends
                isScrolling = setTimeout(function() {
                    // Run the callback
                    callback();
                }, 66);
            }, false);
        };