var start;
    window.onload = function () {
        if(document.all) {//简单判断是否是IE
            start = setInterval('updateImg()', 1000);
        } else {
            alert('FF OK');
        }
    }
    function updateImg() {
        
        if (document.readyState == "complete") {
            try{
                alert('IE OK');
                clearInterval(start);//执行成功，清除监听
            }catch(err){
                return true;
            }
        }
    }