<!DOCTYPE html>
<html>
<head>
<title>图片上传预览</title>
<meta charset="utf-8">
<script type="text/javascript" src="jquery-1.8.3.min.js"></script>
<script type="text/javascript">
$(function() {
$("#file_upload").change(function() {
var $file = $(this);
var fileObj = $file[0];
var windowURL = window.URL || window.webkitURL;
var dataURL;
var $img = $("#preview");
if(fileObj && fileObj.files && fileObj.files[0]){
dataURL = windowURL.createObjectURL(fileObj.files[0]);
$img.attr('src',dataURL);
}else{
dataURL = $file.val();
// $img.css("filter",'progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod = scale,src="' + dataURL + '")');
// 或var imgObj = document.getElementById("preview");
// imgObj.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale,src="" + dataURL + "")";
var imgObj = document.getElementById("preview");
// 两个坑:
// 1、在设置filter属性时，元素必须已经存在在DOM树中，动态创建的Node，也需要在设置属性前加入到DOM中，先设置属性在加入，无效；
// 2、src属性需要像下面的方式添加，上面的两种方式添加，无效；
imgObj.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale)";
imgObj.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = dataURL;
}
});
});
</script>
</head>
<body>
<div id="demo">
<input id="file_upload" type="file" />
<div class="image_container">
<img id="preview" style=" 300px;height: 300px;">
</div>
</div>
</body>
</html>
<!DOCTYPE html>
<html>
<head>
<title>图片上传预览</title>
<meta charset="utf-8">
<script type="text/javascript" src="jquery-1.8.3.min.js"></script>
<script type="text/javascript">
function checkType(upload){
var image = document.getElementById(upload).value;
var extStart = image.lastIndexOf(".");
var ext = image.substring(extStart, image.length).toUpperCase();
if ( ext != ".PNG" && ext != ".GIF" && ext != ".JPG" && ext != ".JPEG") {
alert("图片限于png，gif，jpeg，jpg格式！");
return false;
}
return true;
}
function setImagePreview(upload,preview) {
if(checkType(upload)){
var docObj=document.getElementById(upload);
var imgObjPreview=document.getElementById(preview);
imgObjPreview.style.display = 'block';
imgObjPreview.style.width = '160px';
imgObjPreview.style.height = '120px';
if(docObj.files && docObj.files[0]){
try{
imgObjPreview.src = docObj.files[0].getAsDataURL();
}catch(e){
//火狐7以上版本不能用上面的getAsDataURL()方式获取，需要以下方式
imgObjPreview.src = window.URL.createObjectURL(docObj.files[0]);
}
}else{
//IE下，使用滤镜
docObj.select();
var imgSrc = document.selection.createRange().text;
//图片异常的捕捉，防止用户修改后缀来伪造图片
try{
imgObjPreview.style.filter="progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale)";
imgObjPreview.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = imgSrc;
}catch(e){
alert("您上传的图片格式不正确，请重新选择!");
return false;
}
document.selection.empty();
}
return true;
}
}
</script>
</head>
<body>
<div id="demo">
<input id="file_upload" type="file" onchange="setImagePreview('file_upload','preview')" />
<div class="image_container">
<img id="preview">
</div>
</div>
</body>
</html>