即时显示缩略图
上传图片立即显示图片缩略图，支持火狐和IE
chrome暂时不支持
演示接口：http://www.laruence.com/wp-content/uploads/previewDemo.html
<html>
<head>
<meta content="text/html; charset=utf-8" http-equiv=content-type>
<meta name=author content="Laruence(www.laruence.com)">
<title>即时显示缩略图</title>
</head>
<body>
<div class='previewDemo'>
<input id="file" type="file" onchange="preivew(this, document.getElementById('img'));">
<img id="img" style="visibility:hidden" height="100px" width="100px">
</div>
<script language="javascript" type="text/javascript">
var allowExt = ['jpg', 'gif', 'bmp', 'png', 'jpeg'];
var preivew = function(file, container){
try{
var pic = new Picture(file, container);
}catch(e){
alert(e);
}
}
//缩略图类定义
var Picture = function(file, container){
var height = 0,
widht = 0,
ext = '',
size = 0,
name = '',
path = '';
var self = this;
if(file){
name = file.value;
if (window.navigator.userAgent.indexOf("MSIE")>=1){
file.select();
path = document.selection.createRange().text;
}else if(window.navigator.userAgent.indexOf("Firefox")>=1){
if(file.files){
path = file.files.item(0).getAsDataURL();
}else{
path = file.value;
}
}
}else{
throw "bad file";
}
ext = name.substr(name.lastIndexOf("."), name.length);
if(container.tagName.toLowerCase() != 'img'){
throw "container is not a valid img label";
container.visibility = 'hidden';
}
container.src = path;
container.alt = name;
container.style.visibility = 'visible';
height = container.height;
widht = container.widht;
size = container.fileSize;
this.get = function(name){
return self[name];
}
this.isValid = function(){
if(allowExt.indexOf(self.ext) !== -1){
throw 'the ext is not allowed to upload';
return false;
}
}
}
</script>
</body>
</html>
