这是一个面向对象的JS拖拽库，可设置水平锁定、垂直锁定、锁定位置、锁定范围等，设定这些范围后，只能在设定的模式下拖动，我觉得这是个挺不错的拖拽实例。
运行效果截图如下：
在线演示地址如下：
具体代码如下：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>拖拽库</title> <style type="text/css"> div,h2,p{margin:0;padding:0;} body{font:14px/1.5 arial;} #box{width:100px;height:100px;background:#fef4eb;padding:5px;margin:50px;border:1px solid #f60;} #box .title{height:25px;background:#f60;} #tool{margin-bottom:10px;} </style> <script type="text/javascript"> function Drag() { //初始化 this.initialize.apply(this, arguments) } Drag.prototype = { //初始化 initialize : function (drag, options) { this.drag = this.$(drag); this._x = this._y = 0; this._moveDrag = this.bind(this, this.moveDrag); this._stopDrag = this.bind(this, this.stopDrag); this.setOptions(options); this.handle = this.$(this.options.handle); this.maxContainer = this.$(this.options.maxContainer); this.maxTop = Math.max(this.maxContainer.clientHeight, this.maxContainer.scrollHeight) - this.drag.offsetHeight; this.maxLeft = Math.max(this.maxContainer.clientWidth, this.maxContainer.scrollWidth) - this.drag.offsetWidth; this.limit = this.options.limit; this.lockX = this.options.lockX; this.lockY = this.options.lockY; this.lock = this.options.lock; this.onStart = this.options.onStart; this.onMove = this.options.onMove; this.onStop = this.options.onStop; this.handle.style.cursor = "move"; this.changeLayout(); this.addHandler(this.handle, "mousedown", this.bind(this, this.startDrag)) }, changeLayout : function () { this.drag.style.top = this.drag.offsetTop + "px"; this.drag.style.left = this.drag.offsetLeft + "px"; this.drag.style.position = "absolute"; this.drag.style.margin = "0" }, startDrag : function (event) { var event = event || window.event; this._x = event.clientX - this.drag.offsetLeft; this._y = event.clientY - this.drag.offsetTop; this.addHandler(document, "mousemove", this._moveDrag); this.addHandler(document, "mouseup", this._stopDrag); event.preventDefault && event.preventDefault(); this.handle.setCapture && this.handle.setCapture(); this.onStart() }, moveDrag : function (event) { var event = event || window.event; var iTop = event.clientY - this._y; var iLeft = event.clientX - this._x; if (this.lock) return; this.limit && (iTop < 0 && (iTop = 0), iLeft < 0 && (iLeft = 0), iTop > this.maxTop && (iTop = this.maxTop), iLeft > this.maxLeft && (iLeft = this.maxLeft)); this.lockY || (this.drag.style.top = iTop + "px"); this.lockX || (this.drag.style.left = iLeft + "px"); event.preventDefault && event.preventDefault(); this.onMove() }, stopDrag : function () { this.removeHandler(document, "mousemove", this._moveDrag); this.removeHandler(document, "mouseup", this._stopDrag); this.handle.releaseCapture && this.handle.releaseCapture(); this.onStop() }, //参数设置 setOptions : function (options) { this.options = { handle: this.drag, //事件对象 limit: true, //锁定范围 lock: false, //锁定位置 lockX: false, //锁定水平位置 lockY: false, //锁定垂直位置 maxContainer: document.documentElement || document.body, //指定限制容器 onStart: function () {}, //开始时回调函数 onMove: function () {}, //拖拽时回调函数 onStop: function () {} //停止时回调函数 }; for (var p in options) this.options[p] = options[p] }, //获取id $ : function (id) { return typeof id === "string" ? document.getElementById(id) : id }, //添加绑定事件 addHandler : function (oElement, sEventType, fnHandler) { return oElement.addEventListener ? oElement.addEventListener(sEventType, fnHandler, false) : oElement.attachEvent("on" + sEventType, fnHandler) }, //删除绑定事件 removeHandler : function (oElement, sEventType, fnHandler) { return oElement.removeEventListener ? oElement.removeEventListener(sEventType, fnHandler, false) : oElement.detachEvent("on" + sEventType, fnHandler) }, //绑定事件到对象 bind : function (object, fnHandler) { return function () { return fnHandler.apply(object, arguments) } } }; //应用 window.onload = function () { var oBox = document.getElementById("box"); var oTitle = oBox.getElementsByTagName("h2")[0]; var oSpan = document.getElementsByTagName("span")[0]; var oDrag = new Drag(oBox, {handle:oTitle, limit:false}); var aInput = document.getElementsByTagName("input"); //锁定范围接口 aInput[0].onclick = function () { oDrag.limit = !oDrag.limit; this.value = oDrag.limit ? "取消锁定范围" : "锁定范围" }; //水平锁定接口 aInput[1].onclick = function () { oDrag.lockX = !oDrag.lockX; this.value = oDrag.lockX ? "取消水平锁定" : "水平锁定" }; //垂直锁定接口 aInput[2].onclick = function () { oDrag.lockY = !oDrag.lockY; this.value = oDrag.lockY ? "取消垂直锁定" : "垂直锁定" }; //锁定位置接口 aInput[3].onclick = function () { oDrag.lock = !oDrag.lock; this.value = oDrag.lock ? "取消锁定位置" : "锁定位置" }; //开始拖拽时方法 oDrag.onStart = function () { oSpan.innerHTML = "开始拖拽" }; //开始拖拽时方法 oDrag.onMove = function () { oSpan.innerHTML = "left:" + this.drag.offsetLeft + ", top:" + this.drag.offsetTop }; //开始拖拽时方法 oDrag.onStop = function () { oSpan.innerHTML = "结束拖拽" }; }; </script> </head> <body> <div> <input type="button" value="锁定范围" /> <input type="button" value="水平锁定" /> <input type="button" value="垂直锁定" /> <input type="button" value="锁定位置" /> </div> <p>拖放状态：<span>未开始</span></p> <div> <h2></h2> </div> </body> </html>