jQuery 页面载入进度条 (必有一款适合你----综合搜集版)

链接主题：

预加载图片

延迟加载图片 Lazy Load

javascript图片浏览器的核心——图片预加载

第一种方法：

页面 Loading 条基本人人都会用。它的原理很简单：在页头放置一个文字或者图片的 loading 状态，然后页尾载入一段 JS 隐藏掉，即根据浏览器的载入顺序来实现的简易 Loading 状态条。

loading Process traditional

上图展示了传统 Wordpress 模板在浏览器中的载入顺序，Loading 条的出现和消失分布于头尾。

new loading bar

如果我们在页面的不同位置放置多个 JS ，每个 JS 用于逐步增加 Loading 条的宽度，那么这个 Loading 条无疑会更具实用价值。它在一定程度上缓解了访客等待载入的枯燥感，同时还能客观反映页面载入的进度。若再配以 jQuery 内建的动画效果，其完全可以与浏览器自带的状态条媲美。

先来看一个演示：地址。

要得到演示上的进度条效果，首先，引入 jQuery 框架(一定要放在页头 <head> 标签内)。然后在 <body> 标签起始位置放置：

CSS 可以这么写：

#loading {
width:100px;
height:20px;
background:#A0DB0E;
padding:5px;
position:fixed;
left:0;
top:0;
}
#loading div {
width:1px;
height:20px;
background:#F1FF4D;
}

准备工作到这里就做好了。

接着，请随意发挥，依照你对图二的理解，在模板各个部分的适当位置放置：

其中红色数值应该随载入顺序逐步增加，直到 footer.php。另外别忘了在 footer.php 最末尾放上：

用于载入完毕后隐藏进度条。

第二种

<!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>
<title>Loading Status Bar</title>
<meta name="robots" content="noindex,follow" />
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.2.6/jquery.min.js"></script>
<script type="text/javascript">document.writeln("<style type=\"text\/css\">#loading{width:100px;height:20px;background:#A0DB0E;padding:5px;position:fixed;left:0;top:0}#loading div{width:1px;height:20px;background:#F1FF4D;font:10px/20px Arial}<\/style>");
</script><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /></head>
<body>
<noscript>您的浏览器不支持 Javascript</noscript><div id="loading"><div></div>
</div><? for($i=0;$i<100000;$i++){ echo $i;} ?><script type="text/javascript">$("#loading div").animate({width:"16px"}).text("16%")</script>
<? echo '<br><br><br>'; for($i=0;$i<100000;$i++){ echo $i;} ?><script type="text/javascript">setTimeout(function(){$("#loading div").animate({width:"34px"}).text("34%")},500)</script>
<script type="text/javascript">setTimeout(function(){$("#loading div").animate({width:"67px"}).text("67%")},1000)</script>
<script type="text/javascript">setTimeout(function(){$("#loading div").animate({width:"82px"}).text("82%")},1500)</script>
<script type="text/javascript">setTimeout(function(){$("#loading div").animate({width:"100px"}).text("100%")},2000)</script>
<script type="text/javascript">setTimeout(function(){$("#loading").hide(500)},3000)</script></body>
</html>

第三种导向型

<!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>Loading</title>
<style type="text/css">
.proccess{border:1px solid;width:8px;height:8px;background:#ffffff;margin:3px;
}
</style><script language="JavaScript">var url = 'http://deographics.com/';
</script></head><body  onLoad="location.href = url;" style='overflow:hidden; overflow-y:hidden'><div align=center><font class=fontbig>友情提示，页面正在加载中，请等待......</font><div align="center"><form method="post" name="proccess"><script type="text/javascript"> for(i=0;i<30;i++){document.write("<input class=proccess>");}</script></form></div><div align="center"><script language=JavaScript>var p=0,j=0;var c=new Array('lightskyblue','white')setInterval('proccess();',100)function proccess(){document.forms.proccess.elements[p].style.background=c[j]; p+=1;if(p==30){ p=0;j=1-j; }}</script></div></div><div align="center"><script>if (document.layers){document.write('<Layer src="' + url + ' " visibility="hide"> </Layer>');}else if (document.all || document.getElementById){document.write('<iframe src="' + url + '" style="visibility: hidden;"></iframe>');}else{location.href = url;}</script></div>
</body>
</html>

第四种 iframe loading

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Iframe Loading</title>
</head><body>   <div id="load"><img src="http://sysimages.tq.cn/images/analysis_images/ajax-loader.gif" />&nbsp;loading...</div><iframe style="visibility:hidden" onreadystatechange="stateChangeIE(this)" οnlοad="stateChangeFirefox(this)" name="callframe" id="callframe" width="420" height="100" frameborder="0" scrolling="no" marginheight="0"></iframe><script>   function stateChangeIE(_frame){if (_frame.readyState=="interactive"){ //state: loading ,interactive, completevar loader = document.getElementById("load");loader.innerHTML  = "";loader.style.display = "none";  _frame.style.visibility = "visible";   }   }function stateChangeFirefox(_frame){var loader = document.getElementById("load");loader.innerHTML  = "";loader.style.display = "none";  _frame.style.visibility = "visible";   }callframe.location.href="http://deographics.com/";</script>
</body>
</html>

解释：

0: (Uninitialized) the send( ) method has not yet been invoked.
1: (Loading) the send( ) method has been invoked, request in progress.
2: (Loaded) the send( ) method has completed, entire response received.
3: (Interactive) the response is being parsed.
4: (Completed) the response has been parsed, is ready for harvesting.

0 －（未初始化）还没有调用send()方法
1 －（载入）已调用send()方法，正在发送请求
2 －（载入完成）send()方法执行完成，已经接收到全部响应内容
3 －（交互）正在解析响应内容
4 －（完成）响应内容解析完成，可以在客户端调用了

第五种加载图片

<html>
<head>
<title>JavaScript图片预加载代码，显示loading</title><style type="text/css">div{border:#aaaaaa 3px solid;width:200px;padding:2px;margin:2px 9px;font-size:12px;line-height:22px;color:#999999;}.ipt1{width:160px;font-size:12px;color:#1F6478;border:#999999 1px solid;margin-left:9px;}.ipt2{border:#999999 1px solid;margin-left:6px;color:#666666；}p{margin:0px;padding:0px;background-image:url(http://www.codefans.net/jscss/demoimg/loading.gif);background-position:center;background-repeat:no-repeat;width:200px;height:200px;text-align:center;font-size:12px;color:#999999;line-height:26px;}
</style><script language="javascript" type="text/javascript">function preloadimg(url,obj,ipt){var img = new Image();obj.innerHTML = "<p>Loading...</p>";img.onload = function(){obj.innerHTML = "";obj.style.width = String(img.width)+"px";ipt.style.width = String(img.width-40)+"px";obj.appendChild(img);};img.onerror = function(){obj.innerHTML="Loading Fail !"};img.src = url; //img.src 一定要写在img.onload之后，否则在IE中会出现问题}function show(){var div = document.getElementsByTagName("div")[0];var input = document.getElementsByTagName("input");preloadimg("http://www.codefans.net/jscss/demoimg/wall9.jpg",div,input[0]);input[0].onclick = function(){this.value=""};input[1].onclick = function(){preloadimg(input[0].value,div,input[0]);}}window.onload = show;
</script></head><body>
<div></div><br />
<input type="text" value="将图片地址粘贴在这里" class="ipt1"/><input type="button" value="开始加载" class="ipt2"/>
</body>
</html>

或者使用

<script src="jquery-1.3.2.min.js" type="text/javascript"></script>
<script src="MinmyLazyload.js" type="text/javascript"></script>
<body>
<img original="http://justcoding.iteye.com/uploadfiles/20100424-2_20914.jpg">
<img original="http://justcoding.iteye.com/uploadfiles/20100423-1_85399.jpg">
<script type="text/javascript">$("img").lazyload({ placeholder: "img-loader.gif", effect:"fadeIn" });
</script>
</body>

minimylazyload.js 在附件中找

第六种本页

<style>#loading{font-size:12px;color:#FFFFFF;background:#FF0000;position:absolute;top:500px;left:500px; z-index:1002; padding:2px 10px 2px 10px}
</style><body><div id="loading">页面加载中…</div>..........<script type="text/javascript">document.write('<style>#loading{display:none;}</style>');</script>
</body>
</html>