判断图片加载完

<script type="text/javascript">
var obj=new Image();
obj.src="http://www.phpernote.com/uploadfiles/editor/201107240502201179.jpg";
// obj.onreadystatechange=function(){
// if(this.readyState=="complete"){
obj.onload=function(){
alert('图片的宽度为：'+obj.width+'；图片的高度为：'+obj.height);
document.getElementById("mypic").innnerHTML="<img src='"+this.src+"' />";
document.getElementById('p').src=this.src;
}
</script>
<div id="mypic">onloading……</div>
<img id='p' src="">