ifyour/Drag.html

## Drag.html
<!DOCTYPE html>
<html>

<head>
    <title>Drag 实例</title>
    <style type="text/css">
    #box1,
    #box2 {
        width: 100px;
        height: 100px;
        background-color: red;
    }

    #box2 {
        background-color: green;
    }
    </style>
</head>

<body>
    <div id="box1"></div>
    <div id="box2"></div>
    <script>

    ;(function() {
        // 这是一个私有属性，不需要被实例访问
        var transform = getTransform();

        function Drag(selector) {
            // 放在构造函数中的属性，都是属于每一个实例单独拥有
            this.elem = typeof selector == 'Object' ? selector : document.getElementById(selector);
            this.startX = 0;
            this.startY = 0;
            this.sourceX = 0;
            this.sourceY = 0;

            this.init();
        }


        // 原型
        Drag.prototype = {
            constructor: Drag,

            init: function() {
                // 初始时需要做些什么事情
                this.setDrag();
            },

            // 稍作改造，仅用于获取当前元素的属性，类似于getName
            getStyle: function(property) {
                return document.defaultView.getComputedStyle ? document.defaultView.getComputedStyle(this.elem, false)[property] : this.elem.currentStyle[property];
            },

            // 用来获取当前元素的位置信息，注意与之前的不同之处
            getPosition: function() {
                var pos = {
                    x: 0,
                    y: 0
                };
                if (transform) {
                    var transformValue = this.getStyle(transform);
                    if (transformValue == 'none') {
                        this.elem.style[transform] = 'translate(0, 0)';
                    } else {
                        var temp = transformValue.match(/-?\d+/g);
                        pos = {
                            x: parseInt(temp[4].trim()),
                            y: parseInt(temp[5].trim())
                        }
                    }
                } else {
                    if (this.getStyle('position') == 'static') {
                        this.elem.style.position = 'relative';
                    } else {
                        pos = {
                            x: parseInt(this.getStyle('left') ? this.getStyle('left') : 0),
                            y: parseInt(this.getStyle('top') ? this.getStyle('top') : 0)
                        }
                    }
                }

                return pos;
            },

            // 用来设置当前元素的位置
            setPostion: function(pos) {
                if (transform) {
                    this.elem.style[transform] = 'translate(' + pos.x + 'px, ' + pos.y + 'px)';
                } else {
                    this.elem.style.left = pos.x + 'px';
                    this.elem.style.top = pos.y + 'px';
                }
            },

            // 该方法用来绑定事件
            setDrag: function() {
                var self = this;
                this.elem.addEventListener('mousedown', start, false);

                function start(event) {
                    self.startX = event.pageX;
                    self.startY = event.pageY;

                    var pos = self.getPosition();

                    self.sourceX = pos.x;
                    self.sourceY = pos.y;

                    document.addEventListener('mousemove', move, false);
                    document.addEventListener('mouseup', end, false);
                }

                function move(event) {
                    var currentX = event.pageX;
                    var currentY = event.pageY;

                    var distanceX = currentX - self.startX;
                    var distanceY = currentY - self.startY;

                    self.setPostion({
                        x: (self.sourceX + distanceX).toFixed(),
                        y: (self.sourceY + distanceY).toFixed()
                    })
                }

                function end(event) {
                    document.removeEventListener('mousemove', move);
                    document.removeEventListener('mouseup', end);
                    // do other things
                }
            }
        }

        // 私有方法，仅仅用来获取transform的兼容写法
        function getTransform() {
            var transform = '',
                divStyle = document.createElement('div').style,
                transformArr = ['transform', 'webkitTransform', 'MozTransform', 'msTransform', 'OTransform'],

                i = 0,
                len = transformArr.length;

            for (; i < len; i++) {
                if (transformArr[i] in divStyle) {
                    return transform = transformArr[i];
                }
            }

            return transform;
        }

        // 一种对外暴露的方式
        window.Drag = Drag;
    })();

    // 使用：声明2个拖拽实例
    new Drag('box1');
    new Drag('box2');
    </script>
</body>

</html>
	<!DOCTYPE html>
	<html>

	<head>
	<title>Drag 实例</title>
	<style type="text/css">
	#box1,
	#box2 {
	width: 100px;
	height: 100px;
	background-color: red;
	}

	#box2 {
	background-color: green;
	}
	</style>
	</head>

	<body>
	<div id="box1"></div>
	<div id="box2"></div>
	<script>

	;(function() {
	// 这是一个私有属性，不需要被实例访问
	var transform = getTransform();

	function Drag(selector) {
	// 放在构造函数中的属性，都是属于每一个实例单独拥有
	this.elem = typeof selector == 'Object' ? selector : document.getElementById(selector);
	this.startX = 0;
	this.startY = 0;
	this.sourceX = 0;
	this.sourceY = 0;

	this.init();
	}


	// 原型
	Drag.prototype = {
	constructor: Drag,

	init: function() {
	// 初始时需要做些什么事情
	this.setDrag();
	},

	// 稍作改造，仅用于获取当前元素的属性，类似于getName
	getStyle: function(property) {
	return document.defaultView.getComputedStyle ? document.defaultView.getComputedStyle(this.elem, false)[property] : this.elem.currentStyle[property];
	},

	// 用来获取当前元素的位置信息，注意与之前的不同之处
	getPosition: function() {
	var pos = {
	x: 0,
	y: 0
	};
	if (transform) {
	var transformValue = this.getStyle(transform);
	if (transformValue == 'none') {
	this.elem.style[transform] = 'translate(0, 0)';
	} else {
	var temp = transformValue.match(/-?\d+/g);
	pos = {
	x: parseInt(temp[4].trim()),
	y: parseInt(temp[5].trim())
	}
	}
	} else {
	if (this.getStyle('position') == 'static') {
	this.elem.style.position = 'relative';
	} else {
	pos = {
	x: parseInt(this.getStyle('left') ? this.getStyle('left') : 0),
	y: parseInt(this.getStyle('top') ? this.getStyle('top') : 0)
	}
	}
	}

	return pos;
	},

	// 用来设置当前元素的位置
	setPostion: function(pos) {
	if (transform) {
	this.elem.style[transform] = 'translate(' + pos.x + 'px, ' + pos.y + 'px)';
	} else {
	this.elem.style.left = pos.x + 'px';
	this.elem.style.top = pos.y + 'px';
	}
	},

	// 该方法用来绑定事件
	setDrag: function() {
	var self = this;
	this.elem.addEventListener('mousedown', start, false);

	function start(event) {
	self.startX = event.pageX;
	self.startY = event.pageY;

	var pos = self.getPosition();

	self.sourceX = pos.x;
	self.sourceY = pos.y;

	document.addEventListener('mousemove', move, false);
	document.addEventListener('mouseup', end, false);
	}

	function move(event) {
	var currentX = event.pageX;
	var currentY = event.pageY;

	var distanceX = currentX - self.startX;
	var distanceY = currentY - self.startY;

	self.setPostion({
	x: (self.sourceX + distanceX).toFixed(),
	y: (self.sourceY + distanceY).toFixed()
	})
	}

	function end(event) {
	document.removeEventListener('mousemove', move);
	document.removeEventListener('mouseup', end);
	// do other things
	}
	}
	}

	// 私有方法，仅仅用来获取transform的兼容写法
	function getTransform() {
	var transform = '',
	divStyle = document.createElement('div').style,
	transformArr = ['transform', 'webkitTransform', 'MozTransform', 'msTransform', 'OTransform'],

	i = 0,
	len = transformArr.length;

	for (; i < len; i++) {
	if (transformArr[i] in divStyle) {
	return transform = transformArr[i];
	}
	}

	return transform;
	}

	// 一种对外暴露的方式
	window.Drag = Drag;
	})();

	// 使用：声明2个拖拽实例
	new Drag('box1');
	new Drag('box2');
	</script>
	</body>

	</html>