<html>
<head>
<title>js校验文件格式</title>
<meta http-equiv=‘content-type‘ content=‘text/html;charset=utf-8‘>
<script type="text/javascript" src="jquery-1.4.3.js"></script>
<script type="text/javascript">
function get(){
var s = $("#file1").val();
var fl = s.split(".");
//常用的文件格式
var ary = ["doc","docx","xls","xlsx","ppt","gif","jpeg","jpg","png","txt","wps","pdf"];
//文件格式在数组中返回下标，否则返回 -1
var t= $.inArray(fl[1],ary);
return t==-1;
}
</script>
</head>
<body>
<input type="file" id="file1" >
<input type="button" onclick="get();" value="文件格式">
</body>
</html>原文：http://my.oschina.net/u/2001537/blog/362584