JS实现图片上传预览功能

来源：一二三四网
废话不多说了，直接给大家贴js代码了，具体代码如下所示：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
 <title></title>
</head>
<body>
 <div id="divPreview">
 <img id="imgHeadPhoto" src="noperson.jpg" style="width: 160px; height: 170px; border: solid 1px #d2e2e2;"
 alt="" />
 </div>
 <input type="file" onchange="PreviewImage(this,'imgHeadPhoto','divPreview');" size="20" />
 <script type="text/javascript">
 //js本地图片预览，兼容ie[6-9]、火狐、Chrome17+、Opera11+、Maxthon3
 function PreviewImage(fileObj, imgPreviewId, divPreviewId) {
 var allowExtention = ".jpg,.bmp,.gif,.png"; //允许上传文件的后缀名document.getElementById("hfAllowPicSuffix").value;
 var extention = fileObj.value.substring(fileObj.value.lastIndexOf(".") + 1).toLowerCase();
 var browserVersion = window.navigator.userAgent.toUpperCase();
 if (allowExtention.indexOf(extention) > -1) {
 if (fileObj.files) {//HTML5实现预览，兼容chrome、火狐7+等
 if (window.FileReader) {
 var reader = new FileReader();
 reader.onload = function (e) {
 document.getElementById(imgPreviewId).setAttribute("src", e.target.result);
 }
 reader.readAsDataURL(fileObj.files[0]);
 } else if (browserVersion.indexOf("SAFARI") > -1) {
 alert("不支持Safari6.0以下浏览器的图片预览!");
 }
 } else if (browserVersion.indexOf("MSIE") > -1) {
 if (browserVersion.indexOf("MSIE 6") > -1) {//ie6
 document.getElementById(imgPreviewId).setAttribute("src", fileObj.value);
 } else {//ie[7-9]
 fileObj.select();
 if (browserVersion.indexOf("MSIE 9") > -1)
 fileObj.blur(); //不加上document.selection.createRange().text在ie9会拒绝访问
 var newPreview = document.getElementById(divPreviewId + "New");
 if (newPreview == null) {
 newPreview = document.createElement("div");
 newPreview.setAttribute("id", divPreviewId + "New");
 newPreview.style.width = document.getElementById(imgPreviewId).width + "px";
 newPreview.style.height = document.getElementById(imgPreviewId).height + "px";
 newPreview.style.border = "solid 1px #d2e2e2";
 }
 newPreview.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod='scale',src='" + document.selection.createRange().text + "')";
 var tempDivPreview = document.getElementById(divPreviewId);
 tempDivPreview.parentNode.insertBefore(newPreview, tempDivPreview);
 tempDivPreview.style.display = "none";
 }
 } else if (browserVersion.indexOf("FIREFOX") > -1) {//firefox
 var firefoxVersion = parseFloat(browserVersion.toLowerCase().match(/firefox\/([\d.]+)/)[1]);
 if (firefoxVersion < 7) {//firefox7以下版本
 document.getElementById(imgPreviewId).setAttribute("src", fileObj.files[0].getAsDataURL());
 } else {//firefox7.0+ 
 document.getElementById(imgPreviewId).setAttribute("src", window.URL.createObjectURL(fileObj.files[0]));
 }
 } else {
 document.getElementById(imgPreviewId).setAttribute("src", fileObj.value);
 }
 } else {
 alert("仅支持" + allowExtention + "为后缀名的文件!");
 fileObj.value = ""; //清空选中文件
 if (browserVersion.indexOf("MSIE") > -1) {
 fileObj.select();
 document.selection.clear();
 }
 fileObj.outerHTML = fileObj.outerHTML;
 }
 return fileObj.value; //返回路径
 }
 </script>
</body>
</html>
以上所述是小编给大家介绍的JS实现图片上传预览功能