Dispatching touch events between HTML which contains iframe and the document of that iframe

TouchEventDispatcher.js

/**
@license WTFPL
@author @sou

This library dispatches touch events from an element to another on the different document through iframe.

NOTE:
This library only suports Mobile Safari as each browsers have different specifications for touch event creation.
You might expand _dispatch method if you want to deal with other browsers.

NOTE:
Origins of src attribute of the iframe and HTML you work with should be the same as we need to access contentDocument via iframe.
**/
function TouchEventDispatcher(source, iframe) {
    if (! 'ontouchstart' in source || ! 'contentDocument' in iframe) {
        throw new TypeError("Unexpected type of objects has been passed");
    }
    this._source = source;
    this._iframe = iframe;
    this._listeners = {};
}
TouchEventDispatcher.prototype = {
    start:       TouchEventDispatcher_start,
    end:         TouchEventDispatcher_end,
    listen:      TouchEventDispatcher_listen,
    once:        TouchEventDispatcher_once,
    _reset:      TouchEventDispatcher_reset,
    _dispatch:   TouchEventDispatcher_dispatch,
    handleEvent: TouchEventDispatcher_handleEvent
};

function TouchEventDispatcher_handleEvent(evt) {
    var listeners = this._listeners[evt.type];
    if (listeners) {
        for (var i = 0; i < listeners.every.length; i++) {
            listeners.every[i](evt);
        }
        for (var j = 0; j < listeners.once.length; j++) {
            listeners.once[j](evt);
        }
        listeners.once = [];
    }
}
function TouchEventDispatcher_listen(type, fn, isOnce) {
    if (! this._listeners[type]) {
        this._listeners[type] = {
            every: [],
            once:  []
        };
        this._source.addEventListener(type, this, false);
    }
    if (isOnce) {
        this._listeners[type].once.push(fn);
    }
    else {
        this._listeners[type].every.push(fn);
    }
}
function TouchEventDispatcher_once(type, fn) {
    this.listen(type, fn, true);
}
function TouchEventDispatcher_start() {
    var that = this;
    this.listen('touchstart', function (evt) {
        that._touched = true;
        var t = evt.touches[0];
        if (t) {
            that._point = [t.clientX, t.clientY];
            that._dispatch('touchstart');
        }
    });
    this.listen('touchmove', function (evt) {
        if (this._touched) {
            var t = evt.touches[0];
            if (t) {
                that._point = [t.clientX, t.clientY];
            }
            // dispatching touchmove costs so high that we do not support it by default
            // that._dispatch('touchmove');
        }
    });
    this.listen('touchend', function (evt) {
        if (that._touched) {
            that._dispatch('touchend');
        }
        that._reset();
    });
    this.listen('touchcancel', function (evt) {
        that._reset();
    });
}
function TouchEventDispatcher_end() {
    var types = this._listeners;
    for (var i = 0; i < types.length; i++) {
        this._source.removeEventListener(types[i], this);
    }
    this._reset();
}
function TouchEventDispatcher_reset() {
    this._point   = [null, null];
    this._touched = false;
}

function TouchEventDispatcher_dispatch(type) {
    var identifier = Date.now();
    var x = this._point[0], y = this._point[1];

    var doc = this._iframe.contentDocument;
    var touch = doc.createTouch(
        doc.defaultView, // view
        doc.body,
        identifier,
        x, y, x, y
    );
    var touches = doc.createTouchList(touch);
    var evt = doc.createEvent('TouchEvent');
    evt.initTouchEvent(
        type,                 // {String}    type
        true,                 // {Boolean}   canBubble
        true,                 // {Boolean}   cancelable
        doc.defaultView,      // {Window}    view
        1,                    // {Number}    detail
        0,                    // {Number}    screenX
        0,                    // {Number}    screenY
        0,                    // {Number}    clientX
        0,                    // {Number}    clientY
        false,                // {Boolean}   ctrlKey
        false,                // {Boolean}   altKey
        false,                // {Boolean}   shiftKey
        false,                // {Boolean}   metaKey
        touches,              // {TouchList} touches
        touches,              // {TouchList} targetTouches
        touches,              // {TouchList} changedTouches
        0,                    // {Number}    scale(0 - 1)
        0                     // {Number}    rotation
    );
    var elm = doc.elementFromPoint(x, y);
    elm.dispatchEvent(evt);
}