js onloading 效果

//加载状态为complete时移除loading效果
function completeLoading() {
    if (document.readyState == "complete") {
        var loadingMask = document.getElementById('loadingDiv');
        loadingMask.parentNode.removeChild(loadingMask);
    }
}

function onLoading(){
	console.log("test onLoading...");
	//获取浏览器页面可见高度和宽度
	var _PageHeight = document.documentElement.clientHeight,
	    _PageWidth = document.documentElement.clientWidth;
	//计算loading框距离顶部和左部的距离（loading框的宽度为215px，高度为61px）
	var _LoadingTop = _PageHeight > 61 ? (_PageHeight - 61) / 2 : 0,
	    _LoadingLeft = _PageWidth > 215 ? (_PageWidth - 215) / 2 : 0;
	//在页面未加载完毕之前显示的loading Html自定义内容
	var _LoadingHtml = '<div id="loadingDiv" style="position:absolute;left:0;width:100%;height:' + _PageHeight + 'px;top:0;background:#f3f8ff;opacity:1;filter:alpha(opacity=80);z-index:10000;"><div style="position: absolute; cursor1: wait; left: ' + _LoadingLeft + 'px; top:' + _LoadingTop + 'px; width: auto; height: 57px; line-height: 57px; padding-left: 50px; padding-right: 5px; background: #fff url(Image/loading.gif) no-repeat scroll 5px 10px; border: 2px solid #95B8E7; color: #696969; font-family:\'Microsoft YaHei\';">页面加载中，请等待...</div></div>';
	//呈现loading效果
	document.write(_LoadingHtml);

	//window.onload = function () {
//	    var loadingMask = document.getElementById('loadingDiv');
//	    loadingMask.parentNode.removeChild(loadingMask);
	//};

	//监听加载状态改变
	document.onreadystatechange = completeLoading;
}

 

2.在Ajax中调用即可

var strURL = "loginServlet?loginId="+loginId+"&password="+password;
	 var self = this;
	    if (window.XMLHttpRequest) {
	        self.xmlHttpReq = new XMLHttpRequest();
	    }
	    else if (window.ActiveXObject) {
	        self.xmlHttpReq = new ActiveXObject("Microsoft.XMLHTTP");
	    }
	    
	   
	    
	    self.xmlHttpReq.open('GET', strURL, true);
	    self.xmlHttpReq.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
	    self.xmlHttpReq.onreadystatechange = function() {
	        if (self.xmlHttpReq.readyState == 4 ) {
	        	if(self.xmlHttpReq.status==200){
	        		var result = self.xmlHttpReq.responseText;
	        		var a="OK";
	        		if (result==a){
	        			onLoading();//here to use
	        			window.location.href=responseURL;
	        		}else{
	        			responseMsg.innerHTML = result;
	        		}
	        		
	        	}else{
					alert('Ajax Request Error.');
				}
	        }
			
	    }
	    self.xmlHttpReq.send(null);

 

参考：

http://qubernet.blog.163.com/blog/static/1779472842014510392573/