JavaScript图片预加载与显示技术-优快云博客

//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" />

=============

function imgidload()

{

document.getElementById("imgID").style.display = "";

document.getElementById("divloadimg").style.display = "none";

}

</script>

<div id="divloadimg">无标题文档无标题文档无标题文档</div>

var imgID = new Image();

var src = "http://hp.qq.com/hotpic/cdnphoto/201008/3706.jpg?" + Math.random();

imgID.onload = function() {

document.getElementById("imgID").src = src;

//document.getElementById("divloadimg").style.display = "none";

}

imgID.src = src;

</script>

====================

<html>
<head>
<style type="text/css">
div{border:#aaaaaa 3px solid;width:200px;padding:2px;margin:2px 9px;font-size:12px;line-height:22px;color:#999999;}
.ipt1{width:160px;font-size:12px;color:#1F6478;border:#999999 1px solid;margin-left:9px;}
.ipt2{border:#999999 1px solid;margin-left:6px;color:#666666}
p{margin:0px;padding:0px;background-image:url(/jscss/demoimg/loading.gif);background-position:center;background-repeat:no-repeat;width:200px;height:200px;text-align:center;font-size:12px;color:#999999;line-height:26px;}
</style>
<script language="javascript" type="text/javascript">
function preloadimg(url,obj,ipt){
var img=new Image();
obj.innerHTML="<p>图片加载中...</p>";
img.onload=function(){obj.innerHTML="";obj.style.width=String(img.width)+"px";ipt.style.width=String(img.width-40)+"px";obj.appendChild(img);};
img.onerror=function(){obj.innerHTML="图片加载失败！"};
img.src=url; //img.src一定要写在img.onload之后，否则在IE中会出现题目
}
function show(){
var div=document.getElementsByTagName("div")[0];
var input=document.getElementsByTagName("input");
preloadimg("http://www.codefans.net/jscss/demoimg/wall8.jpg",div,input[0]);
input[0].onclick=function(){this.value=""};
input[1].onclick=function(){preloadimg(input[0].value,div,input[0]);}
}
window.onload=show;
</script>
<title>JavaScript图片预加载代码，显示loading</title>
</head>
<body>
<div></div>
<br />
<input type="text" value="将图片地址粘贴在这里" class="ipt1"/><input type="button" value="开始加载" class="ipt2"/>
</body>
</html>