Fire event after scrollling scrollbars or mousewheel with javascript

Question

I would like to know if it is possible to fire an event after the scrolling of a page, when using the scrollbar or mouse-wheel (or with a swipe on a touch device).

Basically, I'd like to detect when the user has stopped scrolling so I can then AJAX-load, rather than loading while scrolling.

It seems that jQuery's .scroll() is firing every time a user scrolls, and it seems clunky to have an event fire all the time. Is there such thing as .onScrollAfter(), synonymous to the .onMouseUp()?

I'd like to know whether this is possible (or if a function already exists) without using a framework, though I would consider one; especially jQuery.

Answer 1

This event does not exist. You can emulate it by using timeouts:

Example (concept code):

(function() {
    var timer;
    /* Basic "listener" */
    function scroll_finish(ev) {
        clearTimeout(timer);
        timer = setTimeout(scroll_finished, 200, ev);
        //200ms. Too small = triggered too fast. Too high = reliable, but slow
    }
    window.onscroll = scroll_finish; // Or addEventListener, it's just a demo

    // Fire "events"
    var thingey = [];
    function scroll_finished(ev) {
        // Function logic
        for (var i=0; i<thingey.length; i++) {
            thingey[i](ev);
        }
    }
    // Add listener
    window.addScrollListener = function(fn) {
        if (typeof fn  === 'function') {
            thingey.push(fn);
        } else {
           throw TypeError('addScrollListener: First argument must be a function.');
        }
    }
    window.removeScrollListener = function(fn) {
        var index = thingey.indexOf(fn);
        if (index !== -1) thingey.splice(index, 1);
    }
})();