js动态加载图片核心代码

objMapHeart.src = obj.getAttribute("ItemImage");
     
//==============图片预加载处理=======================
        
        if (qp_shared.IsIE && objMapHeart.readyState != "complete") {            
            objMapHeart.onreadystatechange = function() {
                //表明图片已经加载完毕 IE6-IE10支持该事件
                if(objMapHeart.readyState == "complete" || objMapHeart.readyState == "loaded"){
                    //操作
                }
            }
        }
        else if(!qp_shared.IsIE && !objMapHeart.complete) {    
            objMapHeart.onload = function() { 
                //浏览器轮询不断监测img的complete属性
                if(objMapHeart.complete) {
                   //操作
                }
            };
        }