【求助】一段js代码IE8兼容问题（选择图片即可显示功能）

以下js实现了选择图片以后，img可以立刻显示出来，用ie8在本地显示，但是在服务器上就不显示，不知道是怎么回事，请指教一下，谢谢了~~
<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;
             }
         }
     }
     function imgshow(ob){
        preivew(ob, document.getElementById('img'));
     }
</script>
<img szr="" id="img" />
<input type="file"   name="uploadfile" id="uploadfile" />