iscroll.js

/*! iScroll v5.1.3 ~ (c) 2008-2014 Matteo Spinelli ~ http://cubiq.org/license */
(function (window, document, Math) {
	var rAF = window.requestAnimationFrame	||
		window.webkitRequestAnimationFrame	||
		window.mozRequestAnimationFrame		||
		window.oRequestAnimationFrame		||
		window.msRequestAnimationFrame		||
		function (callback) { window.setTimeout(callback, 1000 / 60); };

	var utils = (function () {
		var me = {};

		var _elementStyle = document.createElement('div').style;
		var _vendor = (function () {
			var vendors = ['t', 'webkitT', 'MozT', 'msT', 'OT'],
				transform,
				i = 0,
				l = vendors.length;

			for ( ; i < l; i++ ) {
				transform = vendors[i] + 'ransform';
				if ( transform in _elementStyle ) return vendors[i].substr(0, vendors[i].length-1);
			}

			return false;
		})();

		function _prefixStyle (style) {
			if ( _vendor === false ) return false;
			if ( _vendor === '' ) return style;
			return _vendor + style.charAt(0).toUpperCase() + style.substr(1);
		}

		me.getTime = Date.now || function getTime () { return new Date().getTime(); };

		me.extend = function (target, obj) {
			for ( var i in obj ) {
				target[i] = obj[i];
			}
		};

		me.addEvent = function (el, type, fn, capture) {
			el.addEventListener(type, fn, !!capture);
		};

		me.removeEvent = function (el, type, fn, capture) {
			el.removeEventListener(type, fn, !!capture);
		};

		me.prefixPointerEvent = function (pointerEvent) {
			return window.MSPointerEvent ?
			'MSPointer' + pointerEvent.charAt(9).toUpperCase() + pointerEvent.substr(10):
				pointerEvent;
		};

		me.momentum = function (current, start, time, lowerMargin, wrapperSize, deceleration) {
			var distance = current - start,
				speed = Math.abs(distance) / time,
				destination,
				duration;

			deceleration = deceleration === undefined ? 0.0006 : deceleration;

			destination = current + ( speed * speed ) / ( 2 * deceleration ) * ( distance < 0 ? -1 : 1 );
			duration = speed / deceleration;

			if ( destination < lowerMargin ) {
				destination = wrapperSize ? lowerMargin - ( wrapperSize / 2.5 * ( speed / 8 ) ) : lowerMargin;
				distance = Math.abs(destination - current);
				duration = distance / speed;
			} else if ( destination > 0 ) {
				destination = wrapperSize ? wrapperSize / 2.5 * ( speed / 8 ) : 0;
				distance = Math.abs(current) + destination;
				duration = distance / speed;
			}

			return {
				destination: Math.round(destination),
				duration: duration
			};
		};

		var _transform = _prefixStyle('transform');

		me.extend(me, {
			hasTransform: _transform !== false,
			hasPerspective: _prefixStyle('perspective') in _elementStyle,
			hasTouch: 'ontouchstart' in window,
			hasPointer: window.PointerEvent || window.MSPointerEvent, // IE10 is prefixed
			hasTransition: _prefixStyle('transition') in _elementStyle
		});

		// This should find all Android browsers lower than build 535.19 (both stock browser and webview)
		me.isBadAndroid = /Android /.test(window.navigator.appVersion) && !(/Chrome\/\d/.test(window.navigator.appVersion));

		me.extend(me.style = {}, {
			transform: _transform,
			transitionTimingFunction: _prefixStyle('transitionTimingFunction'),
			transitionDuration: _prefixStyle('transitionDuration'),
			transitionDelay: _prefixStyle('transitionDelay'),
			transformOrigin: _prefixStyle('transformOrigin')
		});

		me.hasClass = function (e, c) {
			var re = new RegExp("(^|\\s)" + c + "(\\s|$)");
			return re.test(e.className);
		};

		me.addClass = function (e, c) {
			if ( me.hasClass(e, c) ) {
				return;
			}

			var newclass = e.className.split(' ');
			newclass.push(c);
			e.className = newclass.join(' ');
		};

		me.removeClass = function (e, c) {
			if ( !me.hasClass(e, c) ) {
				return;
			}

			var re = new RegExp("(^|\\s)" + c + "(\\s|$)", 'g');
			e.className = e.className.replace(re, ' ');
		};

		me.offset = function (el) {
			var left = -el.offsetLeft,
				top = -el.offsetTop;

			// jshint -W084
			while (el = el.offsetParent) {
				left -= el.offsetLeft;
				top -= el.offsetTop;
			}
			// jshint +W084

			return {
				left: left,
				top: top
			};
		};

		me.preventDefaultException = function (el, exceptions) {
			for ( var i in exceptions ) {
				if ( exceptions[i].test(el[i]) ) {
					return true;
				}
			}

			return false;
		};

		me.extend(me.eventType = {}, {
			touchstart: 1,
			touchmove: 1,
			touchend: 1,

			mousedown: 2,
			mousemove: 2,
			mouseup: 2,

			pointerdown: 3,
			pointermove: 3,
			pointerup: 3,

			MSPointerDown: 3,
			MSPointerMove: 3,
			MSPointerUp: 3
		});

		me.extend(me.ease = {}, {
			quadratic: {
				style: 'cubic-bezier(0.25, 0.46, 0.45, 0.94)',
				fn: function (k) {
					return k * ( 2 - k );
				}
			},
			circular: {
				style: 'cubic-bezier(0.1, 0.57, 0.1, 1)',	// Not properly "circular" but this looks better, it should be (0.075, 0.82, 0.165, 1)
				fn: function (k) {
					return Math.sqrt( 1 - ( --k * k ) );
				}
			},
			back: {
				style: 'cubic-bezier(0.175, 0.885, 0.32, 1.275)',
				fn: function (k) {
					var b = 4;
					return ( k = k - 1 ) * k * ( ( b + 1 ) * k + b ) + 1;
				}
			},
			bounce: {
				style: '',
				fn: function (k) {
					if ( ( k /= 1 ) < ( 1 / 2.75 ) ) {
						return 7.5625 * k * k;
					} else if ( k < ( 2 / 2.75 ) ) {
						return 7.5625 * ( k -= ( 1.5 / 2.75 ) ) * k + 0.75;
					} else if ( k < ( 2.5 / 2.75 ) ) {
						return 7.5625 * ( k -= ( 2.25 / 2.75 ) ) * k + 0.9375;
					} else {
						return 7.5625 * ( k -= ( 2.625 / 2.75 ) ) * k + 0.984375;
					}
				}
			},
			elastic: {
				style: '',
				fn: function (k) {
					var f = 0.22,
						e = 0.4;

					if ( k === 0 ) { return 0; }
					if ( k == 1 ) { return 1; }

					return ( e * Math.pow( 2, - 10 * k ) * Math.sin( ( k - f / 4 ) * ( 2 * Math.PI ) / f ) + 1 );
				}
			}
		});

		me.tap = function (e, eventName) {
			var ev = document.createEvent('Event');
			ev.initEvent(eventName, true, true);
			ev.pageX = e.pageX;
			ev.pageY = e.pageY;
			e.target.dispatchEvent(ev);
		};

		me.click = function (e) {
			var target = e.target,
				ev;

			if ( !(/(SELECT|INPUT|TEXTAREA)/i).test(target.tagName) ) {
				ev = document.createEvent('MouseEvents');
				ev.initMouseEvent('click', true, true, e.view, 1,
					target.screenX, target.screenY, target.clientX, target.clientY,
					e.ctrlKey, e.altKey, e.shiftKey, e.metaKey,
					0, null);

				ev._constructed = true;
				target.dispatchEvent(ev);
			}
		};

		return me;
	})();

	function IScroll (el, options) {
		this.wrapper = typeof el == 'string' ? document.querySelector(el) : el;
		this.scroller = this.wrapper.children[0];
		this.scrollerStyle = this.scroller.style;		// cache style for better performance

		this.options = {

// INSERT POINT: OPTIONS 

			startX: 0,
			startY: 0,
			scrollY: true,
			directionLockThreshold: 5,
			momentum: true,

			bounce: true,
			bounceTime: 600,
			bounceEasing: '',

			preventDefault: true,
			preventDefaultException: { tagName: /^(INPUT|TEXTAREA|BUTTON|SELECT)$/ },

			HWCompositing: true,
			useTransition: true,
			useTransform: true
		};

		for ( var i in options ) {
			this.options[i] = options[i];
		}

		// Normalize options
		this.translateZ = this.options.HWCompositing && utils.hasPerspective ? ' translateZ(0)' : '';

		this.options.useTransition = utils.hasTransition && this.options.useTransition;
		this.options.useTransform = utils.hasTransform && this.options.useTransform;

		this.options.eventPassthrough = this.options.eventPassthrough === true ? 'vertical' : this.options.eventPassthrough;
		this.options.preventDefault = !this.options.eventPassthrough && this.options.preventDefault;

		// If you want eventPassthrough I have to lock one of the axes
		this.options.scrollY = this.options.eventPassthrough == 'vertical' ? false : this.options.scrollY;
		this.options.scrollX = this.options.eventPassthrough == 'horizontal' ? false : this.options.scrollX;

		// With eventPassthrough we also need lockDirection mechanism
		this.options.freeScroll = this.options.freeScroll && !this.options.eventPassthrough;
		this.options.directionLockThreshold = this.options.eventPassthrough ? 0 : this.options.directionLockThreshold;

		this.options.bounceEasing = typeof this.options.bounceEasing == 'string' ? utils.ease[this.options.bounceEasing] || utils.ease.circular : this.options.bounceEasing;

		this.options.resizePolling = this.options.resizePolling === undefined ? 60 : this.options.resizePolling;

		if ( this.options.tap === true ) {
			this.options.tap = 'tap';
		}

// INSERT POINT: NORMALIZATION

		// Some defaults
		this.x = 0;
		this.y = 0;
		this.directionX = 0;
		this.directionY = 0;
		this._events = {};

// INSERT POINT: DEFAULTS

		this._init();
		this.refresh();

		this.scrollTo(this.options.startX, this.options.startY);
		this.enable();
	}

	IScroll.prototype = {
		version: '5.1.3',

		_init: function () {
			this._initEvents();

// INSERT POINT: _init

		},

		destroy: function () {
			this._initEvents(true);

			this._execEvent('destroy');
		},

		_transitionEnd: function (e) {
			if ( e.target != this.scroller || !this.isInTransition ) {
				return;
			}

			this._transitionTime();
			if ( !this.resetPosition(this.options.bounceTime) ) {
				this.isInTransition = false;
				this._execEvent('scrollEnd');
			}
		},

		_start: function (e) {
			// React to left mouse button only
			if ( utils.eventType[e.type] != 1 ) {
				if ( e.button !== 0 ) {
					return;
				}
			}

			if ( !this.enabled || (this.initiated && utils.eventType[e.type] !== this.initiated) ) {
				return;
			}

			if ( this.options.preventDefault && !utils.isBadAndroid && !utils.preventDefaultException(e.target, this.options.preventDefaultException) ) {
				e.preventDefault();
			}

			var point = e.touches ? e.touches[0] : e,
				pos;

			this.initiated	= utils.eventType[e.type];
			this.moved		= false;
			this.distX		= 0;
			this.distY		= 0;
			this.directionX = 0;
			this.directionY = 0;
			this.directionLocked = 0;

			this._transitionTime();

			this.startTime = utils.getTime();

			if ( this.options.useTransition && this.isInTransition ) {
				this.isInTransition = false;
				pos = this.getComputedPosition();
				this._translate(Math.round(pos.x), Math.round(pos.y));
				this._execEvent('scrollEnd');
			} else if ( !this.options.useTransition && this.isAnimating ) {
				this.isAnimating = false;
				this._execEvent('scrollEnd');
			}

			this.startX    = this.x;
			this.startY    = this.y;
			this.absStartX = this.x;
			this.absStartY = this.y;
			this.pointX    = point.pageX;
			this.pointY    = point.pageY;

			this._execEvent('beforeScrollStart');
		},

		_move: function (e) {
			if ( !this.enabled || utils.eventType[e.type] !== this.initiated ) {
				return;
			}

			if ( this.options.preventDefault ) {	// increases performance on Android? TODO: check!
				e.preventDefault();
			}

			var point		= e.touches ? e.touches[0] : e,
				deltaX		= point.pageX - this.pointX,
				deltaY		= point.pageY - this.pointY,
				timestamp	= utils.getTime(),
				newX, newY,
				absDistX, absDistY;

			this.pointX		= point.pageX;
			this.pointY		= point.pageY;

			this.distX		+= deltaX;
			this.distY		+= deltaY;
			absDistX		= Math.abs(this.distX);
			absDistY		= Math.abs(this.distY);

			// We need to move at least 10 pixels for the scrolling to initiate
			if ( timestamp - this.endTime > 300 && (absDistX < 10 && absDistY < 10) ) {
				return;
			}

			// If you are scrolling in one direction lock the other
			if ( !this.directionLocked && !this.options.freeScroll ) {
				if ( absDistX > absDistY + this.options.directionLockThreshold ) {
					this.directionLocked = 'h';		// lock horizontally
				} else if ( absDistY >= absDistX + this.options.directionLockThreshold ) {
					this.directionLocked = 'v';		// lock vertically
				} else {
					this.directionLocked = 'n';		// no lock
				}
			}

			if ( this.directionLocked == 'h' ) {
				if ( this.options.eventPassthrough == 'vertical' ) {
					e.preventDefault();
				} else if ( this.options.eventPassthrough == 'horizontal' ) {
					this.initiated = false;
					return;
				}

				deltaY = 0;
			} else if ( this.directionLocked == 'v' ) {
				if ( this.options.eventPassthrough == 'horizontal' ) {
					e.preventDefault();
				} else if ( this.options.eventPassthrough == 'vertical' ) {
					this.initiated = false;
					return;
				}

				deltaX = 0;
			}

			deltaX = this.hasHorizontalScroll ? deltaX : 0;
			deltaY = this.hasVerticalScroll ? deltaY : 0;

			newX = this.x + deltaX;
			newY = this.y + deltaY;

			// Slow down if outside of the boundaries
			if ( newX > 0 || newX < this.maxScrollX ) {
				newX = this.options.bounce ? this.x + deltaX / 3 : newX > 0 ? 0 : this.maxScrollX;
			}
			if ( newY > 0 || newY < this.maxScrollY ) {
				newY = this.options.bounce ? this.y + deltaY / 3 : newY > 0 ? 0 : this.maxScrollY;
			}

			this.directionX = deltaX > 0 ? -1 : deltaX < 0 ? 1 : 0;
			this.directionY = deltaY > 0 ? -1 : deltaY < 0 ? 1 : 0;

			if ( !this.moved ) {
				this._execEvent('scrollStart');
			}

			this.moved = true;

			this._translate(newX, newY);

			/* REPLACE START: _move */

			if ( timestamp - this.startTime > 300 ) {
				this.startTime = timestamp;
				this.startX = this.x;
				this.startY = this.y;
			}

			/* REPLACE END: _move */

		},

		_end: function (e) {
			if ( !this.enabled || utils.eventType[e.type] !== this.initiated ) {
				return;
			}

			if ( this.options.preventDefault && !utils.preventDefaultException(e.target, this.options.preventDefaultException) ) {
				e.preventDefault();
			}

			var point = e.changedTouches ? e.changedTouches[0] : e,
				momentumX,
				momentumY,
				duration = utils.getTime() - this.startTime,
				newX = Math.round(this.x),
				newY = Math.round(this.y),
				distanceX = Math.abs(newX - this.startX),
				distanceY = Math.abs(newY - this.startY),
				time = 0,
				easing = '';

			this.isInTransition = 0;
			this.initiated = 0;
			this.endTime = utils.getTime();

			// reset if we are outside of the boundaries
			if ( this.resetPosition(this.options.bounceTime) ) {
				return;
			}

			this.scrollTo(newX, newY);	// ensures that the last position is rounded

			// we scrolled less than 10 pixels
			if ( !this.moved ) {
				if ( this.options.tap ) {
					utils.tap(e, this.options.tap);
				}

				if ( this.options.click ) {
					utils.click(e);
				}

				this._execEvent('scrollCancel');
				return;
			}

			if ( this._events.flick && duration < 200 && distanceX < 100 && distanceY < 100 ) {
				this._execEvent('flick');
				return;
			}

			// start momentum animation if needed
			if ( this.options.momentum && duration < 300 ) {
				momentumX = this.hasHorizontalScroll ? utils.momentum(this.x, this.startX, duration, this.maxScrollX, this.options.bounce ? this.wrapperWidth : 0, this.options.deceleration) : { destination: newX, duration: 0 };
				momentumY = this.hasVerticalScroll ? utils.momentum(this.y, this.startY, duration, this.maxScrollY, this.options.bounce ? this.wrapperHeight : 0, this.options.deceleration) : { destination: newY, duration: 0 };
				newX = momentumX.destination;
				newY = momentumY.destination;
				time = Math.max(momentumX.duration, momentumY.duration);
				this.isInTransition = 1;
			}

// INSERT POINT: _end

			if ( newX != this.x || newY != this.y ) {
				// change easing function when scroller goes out of the boundaries
				if ( newX > 0 || newX < this.maxScrollX || newY > 0 || newY < this.maxScrollY ) {
					easing = utils.ease.quadratic;
				}

				this.scrollTo(newX, newY, time, easing);
				return;
			}

			this._execEvent('scrollEnd');
		},

		_resize: function () {
			var that = this;

			clearTimeout(this.resizeTimeout);

			this.resizeTimeout = setTimeout(function () {
				that.refresh();
			}, this.options.resizePolling);
		},

		resetPosition: function (time) {
			var x = this.x,
				y = this.y;

			time = time || 0;

			if ( !this.hasHorizontalScroll || this.x > 0 ) {
				x = 0;
			} else if ( this.x < this.maxScrollX ) {
				x = this.maxScrollX;
			}

			if ( !this.hasVerticalScroll || this.y > 0 ) {
				y = 0;
			} else if ( this.y < this.maxScrollY ) {
				y = this.maxScrollY;
			}

			if ( x == this.x && y == this.y ) {
				return false;
			}

			this.scrollTo(x, y, time, this.options.bounceEasing);

			return true;
		},

		disable: function () {
			this.enabled = false;
		},

		enable: function () {
			this.enabled = true;
		},

		refresh: function () {
			var rf = this.wrapper.offsetHeight;		// Force reflow

			this.wrapperWidth	= this.wrapper.clientWidth;
			this.wrapperHeight	= this.wrapper.clientHeight;

			/* REPLACE START: refresh */

			this.scrollerWidth	= this.scroller.offsetWidth;
			this.scrollerHeight	= this.scroller.offsetHeight;

			this.maxScrollX		= this.wrapperWidth - this.scrollerWidth;
			this.maxScrollY		= this.wrapperHeight - this.scrollerHeight;

			/* REPLACE END: refresh */

			this.hasHorizontalScroll	= this.options.scrollX && this.maxScrollX < 0;
			this.hasVerticalScroll		= this.options.scrollY && this.maxScrollY < 0;

			if ( !this.hasHorizontalScroll ) {
				this.maxScrollX = 0;
				this.scrollerWidth = this.wrapperWidth;
			}

			if ( !this.hasVerticalScroll ) {
				this.maxScrollY = 0;
				this.scrollerHeight = this.wrapperHeight;
			}

			this.endTime = 0;
			this.directionX = 0;
			this.directionY = 0;

			this.wrapperOffset = utils.offset(this.wrapper);

			this._execEvent('refresh');

			this.resetPosition();

// INSERT POINT: _refresh

		},

		on: function (type, fn) {
			if ( !this._events[type] ) {
				this._events[type] = [];
			}

			this._events[type].push(fn);
		},

		off: function (type, fn) {
			if ( !this._events[type] ) {
				return;
			}

			var index = this._events[type].indexOf(fn);

			if ( index > -1 ) {
				this._events[type].splice(index, 1);
			}
		},

		_execEvent: function (type) {
			if ( !this._events[type] ) {
				return;
			}

			var i = 0,
				l = this._events[type].length;

			if ( !l ) {
				return;
			}

			for ( ; i < l; i++ ) {
				this._events[type][i].apply(this, [].slice.call(arguments, 1));
			}
		},

		scrollBy: function (x, y, time, easing) {
			x = this.x + x;
			y = this.y + y;
			time = time || 0;

			this.scrollTo(x, y, time, easing);
		},

		scrollTo: function (x, y, time, easing) {
			easing = easing || utils.ease.circular;

			this.isInTransition = this.options.useTransition && time > 0;

			if ( !time || (this.options.useTransition && easing.style) ) {
				this._transitionTimingFunction(easing.style);
				this._transitionTime(time);
				this._translate(x, y);
			} else {
				this._animate(x, y, time, easing.fn);
			}
		},

		scrollToElement: function (el, time, offsetX, offsetY, easing) {
			el = el.nodeType ? el : this.scroller.querySelector(el);

			if ( !el ) {
				return;
			}

			var pos = utils.offset(el);

			pos.left -= this.wrapperOffset.left;
			pos.top  -= this.wrapperOffset.top;

			// if offsetX/Y are true we center the element to the screen
			if ( offsetX === true ) {
				offsetX = Math.round(el.offsetWidth / 2 - this.wrapper.offsetWidth / 2);
			}
			if ( offsetY === true ) {
				offsetY = Math.round(el.offsetHeight / 2 - this.wrapper.offsetHeight / 2);
			}

			pos.left -= offsetX || 0;
			pos.top  -= offsetY || 0;

			pos.left = pos.left > 0 ? 0 : pos.left < this.maxScrollX ? this.maxScrollX : pos.left;
			pos.top  = pos.top  > 0 ? 0 : pos.top  < this.maxScrollY ? this.maxScrollY : pos.top;

			time = time === undefined || time === null || time === 'auto' ? Math.max(Math.abs(this.x-pos.left), Math.abs(this.y-pos.top)) : time;

			this.scrollTo(pos.left, pos.top, time, easing);
		},

		_transitionTime: function (time) {
			time = time || 0;

			this.scrollerStyle[utils.style.transitionDuration] = time + 'ms';

			if ( !time && utils.isBadAndroid ) {
				this.scrollerStyle[utils.style.transitionDuration] = '0.001s';
			}

// INSERT POINT: _transitionTime

		},

		_transitionTimingFunction: function (easing) {
			this.scrollerStyle[utils.style.transitionTimingFunction] = easing;

// INSERT POINT: _transitionTimingFunction

		},

		_translate: function (x, y) {
			if ( this.options.useTransform ) {

				/* REPLACE START: _translate */

				this.scrollerStyle[utils.style.transform] = 'translate(' + x + 'px,' + y + 'px)' + this.translateZ;

				/* REPLACE END: _translate */

			} else {
				x = Math.round(x);
				y = Math.round(y);
				this.scrollerStyle.left = x + 'px';
				this.scrollerStyle.top = y + 'px';
			}

			this.x = x;
			this.y = y;

// INSERT POINT: _translate

		},

		_initEvents: function (remove) {
			var eventType = remove ? utils.removeEvent : utils.addEvent,
				target = this.options.bindToWrapper ? this.wrapper : window;

			eventType(window, 'orientationchange', this);
			eventType(window, 'resize', this);

			if ( this.options.click ) {
				eventType(this.wrapper, 'click', this, true);
			}

			if ( !this.options.disableMouse ) {
				eventType(this.wrapper, 'mousedown', this);
				eventType(target, 'mousemove', this);
				eventType(target, 'mousecancel', this);
				eventType(target, 'mouseup', this);
			}

			if ( utils.hasPointer && !this.options.disablePointer ) {
				eventType(this.wrapper, utils.prefixPointerEvent('pointerdown'), this);
				eventType(target, utils.prefixPointerEvent('pointermove'), this);
				eventType(target, utils.prefixPointerEvent('pointercancel'), this);
				eventType(target, utils.prefixPointerEvent('pointerup'), this);
			}

			if ( utils.hasTouch && !this.options.disableTouch ) {
				eventType(this.wrapper, 'touchstart', this);
				eventType(target, 'touchmove', this);
				eventType(target, 'touchcancel', this);
				eventType(target, 'touchend', this);
			}

			eventType(this.scroller, 'transitionend', this);
			eventType(this.scroller, 'webkitTransitionEnd', this);
			eventType(this.scroller, 'oTransitionEnd', this);
			eventType(this.scroller, 'MSTransitionEnd', this);
		},

		getComputedPosition: function () {
			var matrix = window.getComputedStyle(this.scroller, null),
				x, y;

			if ( this.options.useTransform ) {
				matrix = matrix[utils.style.transform].split(')')[0].split(', ');
				x = +(matrix[12] || matrix[4]);
				y = +(matrix[13] || matrix[5]);
			} else {
				x = +matrix.left.replace(/[^-\d.]/g, '');
				y = +matrix.top.replace(/[^-\d.]/g, '');
			}

			return { x: x, y: y };
		},

		_animate: function (destX, destY, duration, easingFn) {
			var that = this,
				startX = this.x,
				startY = this.y,
				startTime = utils.getTime(),
				destTime = startTime + duration;

			function step () {
				var now = utils.getTime(),
					newX, newY,
					easing;

				if ( now >= destTime ) {
					that.isAnimating = false;
					that._translate(destX, destY);

					if ( !that.resetPosition(that.options.bounceTime) ) {
						that._execEvent('scrollEnd');
					}

					return;
				}

				now = ( now - startTime ) / duration;
				easing = easingFn(now);
				newX = ( destX - startX ) * easing + startX;
				newY = ( destY - startY ) * easing + startY;
				that._translate(newX, newY);

				if ( that.isAnimating ) {
					rAF(step);
				}
			}

			this.isAnimating = true;
			step();
		},
		handleEvent: function (e) {
			switch ( e.type ) {
				case 'touchstart':
				case 'pointerdown':
				case 'MSPointerDown':
				case 'mousedown':
					this._start(e);
					break;
				case 'touchmove':
				case 'pointermove':
				case 'MSPointerMove':
				case 'mousemove':
					this._move(e);
					break;
				case 'touchend':
				case 'pointerup':
				case 'MSPointerUp':
				case 'mouseup':
				case 'touchcancel':
				case 'pointercancel':
				case 'MSPointerCancel':
				case 'mousecancel':
					this._end(e);
					break;
				case 'orientationchange':
				case 'resize':
					this._resize();
					break;
				case 'transitionend':
				case 'webkitTransitionEnd':
				case 'oTransitionEnd':
				case 'MSTransitionEnd':
					this._transitionEnd(e);
					break;
				case 'wheel':
				case 'DOMMouseScroll':
				case 'mousewheel':
					this._wheel(e);
					break;
				case 'keydown':
					this._key(e);
					break;
				case 'click':
					if ( !e._constructed ) {
						e.preventDefault();
						e.stopPropagation();
					}
					break;
			}
		}
	};
	IScroll.utils = utils;

	if ( typeof module != 'undefined' && module.exports ) {
		module.exports = IScroll;
	} else {
		window.IScroll = IScroll;
	}

})(window, document, Math);