工作之余，验证了javascript代码在页面中的执行顺序，只要包括四个位置的测试：文档的头部和底部，window.onload中和$().ready()中;
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</title>
<script type="text/javascript">
var s1 = new Date();
//alert("S1:"+s1.getTime());
$('#cs1').val(s1.getTime());
</script>
<script type="text/javascript" src="http://style.org.hc360.com/js/build/source/core/jquery.min.js"></script>
<script type="text/javascript">
window.onload=function(){
var s2 = new Date();
//alert("S2:"+s2.getTime());
$('#cs2').val(s2.getTime());
}
$().ready(function() {
var s3 = new Date();
//alert("S3:"+s3.getTime());
$('#cs3').val(s3.getTime());
});
</script>
</head>
<body>
<input id="cs1" data-log="第一个input"/>
<input id="cs2" data-log="第二个input"/>
<input id="cs3" data-log="第三个input"/>
<input id="cs4" data-log="第四个input"/>
<img src="http://img00.hc360.com/b2b/201209/201209221600084438.jpg" data-log="第一个img"div/>
<img src="http://img00.hc360.com/b2b/201209/201209221601586910.jpg" data-log="第二个img" />
<img src="http://img00.hc360.com/b2b/201209/201209051709119579.jpg" data-log="第三个ing" />
<img src="http://img00.hc360.com/b2b/201209/201209051712521920.jpg" data-log="第三个ing" />
<img src="http://img00.hc360.com/b2b/201209/201209131458144185.jpg" data-log="第三个ing" />
<img src="http://img00.hc360.com/b2b/201209/201209131500093424.jpg" data-log="第三个ing" />
<img src="http://img00.hc360.com/b2b/201209/201209221605226829.jpg" data-log="第三个ing" />
<img src="http://img00.hc360.com/b2b/201209/201209221607425487.jpg" data-log="第三个ing" />
<img src="http://img616.ph.126.net/g9ocgi2F9ovgJ0LofF28mg==/1704612458961497506.jpg" data-log="第三个ing" />
</body>
<script type="text/javascript">
var s4 = new Date();
$('#cs4').val(s4.getTime());
//alert("S4:"+s4.getTime());
</script>
</html>
验证结果如下:
因为头部的javascript执行时dom还没有在页面中渲染，所有s1中没有，显示数据，但是是第一个执行的，可以用alert顺序证明。依次执行的顺序是：S1>S4>S3>S2.