.jmulti-touches.js

var $ = require('jquery');


//global variable to keep track of ongoing touches
var ongoingTouches = {};



$(function() {
    var el = document.body;
    el.addEventListener("touchstart", handleTouchStart, false);
    el.addEventListener("touchend", handleTouchEnd, false);
    el.addEventListener("touchcancel", handleTouchCancel, false);
    el.addEventListener("touchleave", handleTouchEnd, false);
    el.addEventListener("touchmove", handleTouchMove, false);
    log("initialized.");
});


function handleTouchStart(evt) {
    var touches = evt.changedTouches;
    for (var i = 0; i < touches.length; i++) {

        var touchId = touches[i].identifier;
        var touchData = {
            identifier: touches[i].identifier,
            clientX: touches[i].clientX,
            clientY: touches[i].clientY
        };
        ongoingTouches[touchId] = touchData;
        console.log("touchstart:" + i + "...", touchId, touchData);
        evt.preventDefault();
    }
}

function handleTouchMove(evt) {
    var touches = evt.changedTouches;
    for (var i = 0; i < touches.length; i++) {

        var touchId = touches[i].identifier;
        var touchData = ongoingTouches[touchId];

        if (touchData) {
            touchData.clientX = touches[i].clientX;
            touchData.clientY = touches[i].clientY;
            console.log("continuing touch " + touchId, touchData);

        } else {
            console.log("can't figure out which touch to continue");
        }
        evt.preventDefault();
    }
}

function handleTouchEnd(evt) {
    var touches = evt.changedTouches;
    for (var i = 0; i < touches.length; i++) {

        var touchId = touches[i].identifier;
        var touchData = ongoingTouches[touchId];

        if (touchData) {
            ongoingTouches[touchId] = false;
            console.log("ended touch", touchId);
        } else {
            console.log("can't figure out which touch to end");
        }
        evt.preventDefault();
    }
}

function handleTouchCancel(evt) {
    var touches = evt.changedTouches;
    for (var i = 0; i < touches.length; i++) {
        var touchId = touches[i].identifier;
        ongoingTouches[touchId] = false;
        console.log("touchcancel.", touchId);
    }
    evt.preventDefault();
}