ExtJs上传图片预览功能

//上传图片类型var img_reg = /\.([jJ][pP][gG]){1}$|\.([jJ][pP][eE][gG]){1}$|\.([gG][iI][fF]){1}$|\.([pP][nN][gG]){1}$|\.([bB][mM][pP]){1}$/Ext.extend(simpleForm,Ext.form.FormPanel,{listeners:{    'render':function(f)    {        this.form.findField('imageupload').on('render',function()         {               Ext.get('imageupload').on('change',function(field,newValue,oldValue )             {                                                 var url = 'file:///'+Ext.get('imageupload').dom.value;                                                     if(img_reg.test(url))                {                                                                      if(Ext.isIE)                                 {                                      var image = Ext.get('imageBrowse').dom;                                       image.src = Ext.BLANK_IMAGE_URL;//覆盖原来的图片                                       image.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src=url;                                                                             }//支持FF                                 else                                 {                                      Ext.get('imageBrowse').dom.src =Ext.get('imageupload').dom.files.item(0).getAsDataURL()                                 }                   }             },this);           },this);     }}});