<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title> New Document </title>
<meta name="Generator" content="EditPlus">
<meta name="Author" content="">
<meta name="Keywords" content="">
<meta name="Description" content="">
<script type="text/javascript">
</script>
</head>
<body>
<form name="form4" id="form4" method="post" action="#">
<input type="file" name="file4" id="file4" onchange="preview4()" />
<img id="pic4" src="" alt="图片在此显示" width="120"/>
</form>
<script type="text/javascript">
function preview4(){
var x = document.getElementById("file4");
var y = document.getElementById("pic4");
if(!x || !x.value || !y) return;
var patn = /\.jpg$|\.jpeg$|\.gif$/i;
if(patn.test(x.value)){
y.src = "file://localhost/" + x.value;
}else{
alert("您选择的似乎不是图像文件。");
}
}
</script>
</body>
</html>
原文地址：http://www.cnblogs.com/zhangshiwen/p/3847403.html
