JS 非图片动态loading效果实现代码

代码如下：首先实现该功能的js对象LoadingMsg：复制代码代码如下: var Class = { create: function() { return function() { this.init.apply(this,arguments); } } } var LoadingMsg = Class.create(); LoadingMsg.prototype = { init: function(spanId, spanMsg) { this.intervalID = -10000; this.spanId = spanId; this.spanMsg = spanMsg; this.timespan = 1000; this.pointNum = 3; this.initPointMsg = "..."; }, Loading: function() { var maxLength = this.spanMsg.length + this.pointNum; var currentSpanMsg = document.getElementById(this.spanId).innerHTML; if (currentSpanMsg.length < maxLength) { document.getElementById(this.spanId).innerHTML += "."; } else { document.getElementById(this.spanId).innerHTML = this.spanMsg; } }, Start: function() { document.getElementById(this.spanId).innerHTML = this.spanMsg + this.initPointMsg; var callObj = this; this.intervalID = setInterval(function() { callObj.Loading(); }, this.timespan); }, End: function() { document.getElementById(this.spanId).innerHTML = ""; clearInterval(this.intervalID); } } 关键点：如果把复制代码代码如下: var callObj = this; this.intervalID = setInterval(function() { callObj.Loading(); }, this.timespan); 写成：复制代码代码如下: this.intervalID = setInterval(this.Loading, this.timespan); 在执行Loading方法时则会报找不到this.spanMsg的错误。因为在setInterval里的第一个参数里的this是windows对象，而不是LoadingMsg对象。windows.setInterval嘛。应用该方法：复制代码代码如下: <body> <input type="button" value="Start" onclick="javascript:StartLoading();" /> <span id="spanId" style="color:Red"></span> <br /> <input type="button" value="End" onclick="javascript:EndLoading();" /> <br /><br /> <script type="text/javascript"> var loadingMsgObj = new LoadingMsg("spanId","loading"); function StartLoading() { loadingMsgObj.Start(); } function EndLoading() { loadingMsgObj.End(); } </script> </body> 来源于prototype.js里经典创建Js对象的复制代码代码如下: var Class = { create: function() { return function() { this.init.apply(this,arguments); } } } var LoadingMsg = Class.create(); 在Class.create()的时候做了2件事，1个是创建了LoadingMsg的对象，即var LoadingMsg = function() {}；另外一件事就是调用LoadingMsg的init方法，初始化LoadingMsg里的静态私有变量，相当于c#里的构造函数作用。如果你觉得这很装逼的话，如果你更喜欢简单朴实的女孩子的话，也可以改写LoadingMsg对象：复制代码代码如下: var LoadingMsg = function() { }; LoadingMsg.prototype = { init: function(spanId, spanMsg) { this.intervalID = -10000; this.spanId = spanId; this.spanMsg = spanMsg; this.timespan = 1000; this.pointNum = 3; this.initPointMsg = "..."; }, Loading: function() { var maxLength = this.spanMsg.length + this.pointNum; var currentSpanMsg = document.getElementById(this.spanId).innerHTML; if (currentSpanMsg.length < maxLength) { document.getElementById(this.spanId).innerHTML += "."; } else { document.getElementById(this.spanId).innerHTML = this.spanMsg; } }, Start: function(spanId, spanMsg) { this.init(spanId, spanMsg); document.getElementById(this.spanId).innerHTML = this.spanMsg + this.initPointMsg; var callObj = this; this.intervalID = setInterval(function() { callObj.Loading(); }, this.timespan); }, End: function() { document.getElementById(this.spanId).innerHTML = ""; clearInterval(this.intervalID); } } 所不同的是把init的过程调到Start时执行，因此调用的时候也就变成了复制代码代码如下: 　　 var loadingMsgObj = new LoadingMsg(); function StartLoading() { 　　loadingMsgObj.Start("spanId", "loading"); } 从面向对象的习惯上来说，我个人还是倾向第一种写法，在实例化对象的时候即传入参数，而不是执行对象方法的时候传入参数。另外关于setInterval方法传参数时，如果参数是简单的string，可以 setInterval("DisplayXYZ('xyz')",1000); 如果参数是对象，则可以setInterval(function(){DisplayXYZ(obj);},1000); LoadingMsg还是主要用在Ajax中，应用于执行时间可能较长的场景，在发送请求后loadingMsgObj.Start()，在成功获取响应时loadingMsgObj.End()。

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