html5 实现加载loading.......实例
    1.	<!DOCTYPE html> 
2.	<html lang="en" xmlns="http://www.w3.org/1999/xhtml"> 
3.	<head> 
4.	<meta http-equiv="Content-Type" content="text/html;charset=utf-8" /> 
5.	<title>HTML5 Demo: canvas</title> 
6.	<style> 
7.	body {   
8.	  font: normal 16px/20px Helvetica, sans-serif;  
9.	  background: rgb(237, 237, 236);  
10.	  margin: 0;  
11.	  margin-top: 40px;  
12.	  padding: 0;  
13.	}  
14.	 
15.	article, section, header, footer {  
16.	  display: block;  
17.	}  
18.	 
19.	#wrapper {  
20.	  width: 600px;  
21.	  margin: 0 auto;  
22.	  background: #fff url(images/shade.jpg) repeat-x center bottom;  
23.	  -moz-border-radius: 10px;  
24.	  -webkit-border-radius: 10px;  
25.	  border-top: 1px solid #fff;  
26.	  padding-bottom: 76px;  
27.	}  
28.	 
29.	h1 {  
30.	  padding-top: 10px;  
31.	}  
32.	 
33.	h2 {  
34.	  font-size: 100%;  
35.	  font-style: italic;  
36.	}  
37.	 
38.	header,  
39.	article > *,  
40.	footer a,  
41.	footer p {  
42.	  margin: 20px;  
43.	}  
44.	 
45.	footer > * {  
46.	  margin: 20px;  
47.	  color: #999;  
48.	}  
49.	 
50.	article {  
51.	  position: relative;  
52.	}  
53.	</style> 
54.	<script> 
55.	// For discussion and comments, see: http://remysharp.com/2009/01/07/html5-enabling-script/  
56.	(function(){if(!/*@cc_on!@*/0)return;var e = "abbr,article,aside,audio,bb,canvas,datagrid,datalist,details,dialog,eventsource,figure,footer,header,mark,menu,meter,nav,output,progress,section,time,video".split(','),i=e.length;while (i--){document.createElement(e[i])}})()  
57.	</script> 
58.	</head> 
59.	<body> 
60.	<section id="wrapper"> 
61.	    <header> 
62.	      <h1>Canvas</h1> 
63.	 
64.	    </header> 
65.	    <article></article> 
66.	    <footer><a href="/">HTML5 demo</a></footer> 
67.	</section> 
68.	<script src="h5utils.js"></script> 
69.	<script> 
70.	 
71.	buildSpinner({ x : 50, y : 50, size : 20, degrees : 30 });  
72.	 
73.	function buildSpinner(data) {  
74.	    
75.	  var canvas = document.createElement('canvas');  
76.	  canvas.height = 100;  
77.	  canvas.width = 300;  
78.	  document.getElementsByTagName('article')[0].appendChild(canvas);  
79.	  var ctx = canvas.getContext("2d"),  
80.	    i = 0, degrees = data.degrees, loops = 0, degreesList = [];  
81.	      
82.	  for (i = 0; i < degrees; i++) {  
83.	    degreesList.push(i);  
84.	  }  
85.	    
86.	  // reset  
87.	  i = 0;  
88.	    
89.	  // so I can kill it later  
90.	  window.canvasTimer = setInterval(draw, 1000/degrees);    
91.	 
92.	  function reset() {  
93.	    ctx.clearRect(0,0,100,100); // clear canvas  
94.	      
95.	    var left = degreesList.slice(0, 1);&nbs