片在未加载完成前显示加载中为什么,片显示正在加载

// 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 (){}
< / 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 "   / >