JavaScript文件上传插件：实操与进度追踪

 <script type="text/javascript">
       var intervalID = 0;
       var progressBar;
       var fileUpload;
       var form;       
       // 进度条      
       function pageLoad(){           
           $addHandler($get('upload'), 'click', onUploadClick);
           progressBar = $find('progress');
       }
       // 注册表单       
       function register(form, fileUpload){            
           this.form = form;
           this.fileUpload = fileUpload;
       }        
       //上传验证
       function onUploadClick() {        
           var vaild = fileUpload.value.length > 0;
           if(vaild){              
               $get('upload').disabled = 'disabled';             
               updateMessage('info', '初始化上传...');                
               //提交上传
               form.submit();                
               // 隐藏frame
               Sys.UI.DomElement.addCssClass($get('uploadFrame'), 'hidden');
               // 0开始显示进度条
               progressBar.set_percentage(0);
               progressBar.show();           
               // 上传过程
               intervalID = window.setInterval(function(){

                   PageMethods.GetUploadStatus(function(result){
                       if(result){
                           //  更新进度条为新值
                           progressBar.set_percentage(result.percentComplete);
                           //更新信息
                           updateMessage('info', result.message);
                           
                           if(result == 100){
                               // 自动消失
                               window.clearInterval(intervalID);                        
                           }
                       }
                   });
               }, 500);                
           }
           else{
               onComplete('error', '您必需选择一个文件');
           }
       }       
   
       function onComplete(type, msg){
           // 自动消失
           window.clearInterval(intervalID);
           // 显示消息
           updateMessage(type, msg);
           // 隐藏进度条
           progressBar.hide();
           progressBar.set_percentage(0);
           // 重新启用按钮
           $get('upload').disabled = '';