<form name="form1">
<input type="file" name="file1" onchange="checkimage
(value)">
</form>
<script language="javascript">
var img=null;
function checkimage(name){
if(/^.+\.(gif|jpg|png)$/i.test(name))
{
if(img)img.removeNode(true);
img=document.createElement("img");
img.style.position="absolute";
img.style.visibility="hidden";
img.attachEvent("onerror",oe);
img.attachEvent("onreadystatechange",orsc);
document.body.insertAdjacentElement("beforeend",img);
img.src=name;
}
else{oe()}
}
function oe(){
form1.reset();
alert("文件类型只能是<gif><jpg><png>!");
}
function orsc(){
if (img.fileSize>51200){
form1.reset();
alert("文件大小不能超过50K!");
}
}
</script>
