JS实现上传图片实时预览功能

//js本地图片预览，兼容ie[6-9]、火狐、Chrome17+、Opera11+、Maxthon3  function PreviewImage(fileObj) {    //创建dom元素    var divPreviewId = 'divPreview_' + fileObj.name;    var imgPreviewId = 'imgHeadPhoto_' + fileObj.name;    var html='<div id="'+divPreviewId+'">'+          '<img id="'+imgPreviewId+'" src="images/moren.jpg" style="width: 120px; height: 120px; border: solid 1px #d2e2e2;" />'+         '</div>';    $('#'+divPreviewId).remove();    $(fileObj).after(html);    //进行限制    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) {  //格式正确      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) {          $('#'+divPreviewId).remove();          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 {      $('#'+divPreviewId).remove();      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  }