图片在未加载完成前显示“加载中...”

//判断浏览器
var Browser=new Object();
Browser.userAgent=window.navigator.userAgent.toLowerCase();
Browser.ie=/msie/.test(Browser.userAgent);
Browser.Moz=/gecko/.test(Browser.userAgent);

//判断是否加载完成
function Imagess(url,imgid,callback){    
    var val=url;
    var img=new Image();
    if(Browser.ie){
        img.onreadystatechange =function(){  
            if(img.readyState=="complete"||img.readyState=="loaded"){
                callback(img,imgid);
            }
        }        
    }else if(Browser.Moz){
        img.onload=function(){
            if(img.complete==true){
                callback(img,imgid);
            }
        }        
    }    
    //如果因为网络或图片的原因发生异常，则显示该图片
    img.onerror=function(){img.src='http://www.baidu.com/img/baidu_logo.gif'}
    img.src=val;
}

//显示图片
function checkimg(obj,imgid){
document.getElementById(imgid).src=obj.src;
}
//初始化需要显示的图片，并且指定显示的位置
window.onload=function(){
    Imagess("http://hiphotos.baidu.com/lovebyakuya/pic/item/01cf20088f9506f063d98653.jpg","img1",checkimg);
    Imagess("http://hiphotos.baidu.com/lovebyakuya/pic/item/7b7b19c70d62f4fdd0006050.jpg","img2",checkimg);
    Imagess("http://hiphotos.baidu.com/joanne728/pic/item/892557641806d20eaa184c71.jpg","img3",checkimg);
    Imagess("http://www.neocha.com/-/res/Camilla/20071204181216078845_h.jpg","img4",checkimg);
    Imagess("http://www.neocha.com/-/res/Camilla/20071204181216d078845_h.","img5",checkimg);
}
</script>
<img id="img1" src="loading.gif" width="100" height="100" />
<img id="img2" src="loading.gif" width="100" height="100" />
<img id="img3" src="loading.gif" width="100" height="100" />
<img id="img4" src="loading.gif" width="100" height="100" />
<img id="img5" src="loading.gif" width="100" height="100" />