Pad Touch Event

PadTouchEvent.js

var Touch = {
    startPos: null,
    endPos: null,
    init: function (elementID) {
        document.getElementById(elementID)
            .addEventListener('touchstart',

        function (event) {
            Touch.start(event);
        }, false);
        document.getElementById(elementID)
            .addEventListener('touchmove',

        function (event) {
            Touch.update(event);
        }, false);
        document.getElementById(elementID)
            .addEventListener('touchend',

        function (event) {
            Touch.stop(event);
        }, false);
    },
    start: function (event) {
        var touch = event.targetTouches[0];
        this.startPos = {
            x: touch.pageX,
            y: touch.pageY
        };
    },
    update: function (event) {
        var touch = event.targetTouches[0];
        // TODO: record gesture
    },
    stop: function (event) {
        var touch = event.changedTouches[0];
        this.endPos = {
            x: touch.pageX,
            y: touch.pageY
        };

        var gesture = this.analyseGesture();

        alert("The gesture is: " + gesture);
    },
    analyseGesture: function () {
        if (this.startPos && this.endPos) {
            if (this.endPos.x > this.startPos.x + 200) return "swipe right";
            else if (this.endPos.x < this.startPos.x - 200) return "swipe left";
            else return "unknown";
        }
    }
};