Adds the ability to handle swipe events.

swipe.js

//Example Usage
$('#selector').each(function(){
    swipedetect(this, function (swipedir){
        // swipedir contains either "none", "left", "right", "top", or "down"
        if (swipedir =='left') {
            $("#selector").parent().find('.next').click();
        }
        if (swipedir =='right') {
            $("#selector").parent().find('.prev').click();
        }

    });
});



// From http://www.javascriptkit.com/javatutors/touchevents2.shtml
function swipedetect(el, callback){

    var touchsurface = el,
    swipedir,
    startX,
    startY,
    distX,
    distY,
    threshold = 150, //required min distance traveled to be considered swipe
    restraint = 100, // maximum distance allowed at the same time in perpendicular direction
    allowedTime = 300, // maximum time allowed to travel that distance
    elapsedTime,
    startTime,
    handleswipe = callback || function (swipedir){}

    touchsurface.addEventListener('touchstart', function(e){
        var touchobj = e.changedTouches[0];

        swipedir = 'none';
        dist = 0;
        startX = touchobj.pageX;
        startY = touchobj.pageY;
        startTime = new Date().getTime();
        e.preventDefault();

    }, false);

    touchsurface.addEventListener('touchmove', function(e){
        e.preventDefault(); // prevent scrolling when inside DIV
    }, false);

    touchsurface.addEventListener('touchend', function(e){

        var touchobj = e.changedTouches[0];
        distX = touchobj.pageX - startX; // get horizontal dist traveled by finger while in contact with surface
        distY = touchobj.pageY - startY; // get vertical dist traveled by finger while in contact with surface
        elapsedTime = new Date().getTime() - startTime;

        if (elapsedTime <= allowedTime) {

            if (Math.abs(distX) >= threshold && Math.abs(distY) <= restraint) {
                swipedir = (distX < 0)? 'left' : 'right';
            }
            else if (Math.abs(distY) >= threshold && Math.abs(distX) <= restraint){
                swipedir = (distY < 0)? 'up' : 'down'
            }
        }
        handleswipe(swipedir);
        e.preventDefault();
    }, false)
}