如何在解析数据之前延迟显示？

Question

我在向面板解析数据时面临一个小问题,这是我的代码:

Ext.onReady(function(){   

var stockings = [],i=0;
Ext.regModel('Carding', {fields: ['price'] });
var Detailsstore = new Ext.data.Store({
           model: 'Carding',
           proxy: {
               type: 'ajax',
               url: 'http://192.168.1.92/testapp/websample%20backup/sample/assets/www/XMLS/xmlformatses.xml',
               reader: {
                   type: 'xml',
                   record: 'root'
                }
            },
            listeners: {
                single: true,
                datachanged: function(){
                  Detailsstore.each(function(r){
     stockings[i++]=r.get('price');
                    });
                alert(stockings[3]);//This alert works fine
                }
            }    
        });

 Detailsstore.read();

    alert(stockings[3]);//this alert even being placed after the Detailsstore it shows undefined . . . . .

  var showdetails = new Ext.Panel({
     scroll :'vertical',
     flex:7,
     renderTo: 'bubbleCt',
     baseCls: 'kiran',
     stretchX: true,
     html: '<span style="color:#fff; font-size:20px;"><span style="font-size:25px; font-weight: bold;">' + stockings[2] + '</span><br/><br/><span style="font-weight:bold;">Trading Action Plan :</span><br/>&bull; Buy Price: 1 <br/>&bull; Sell Price:2<br/>&bull; Stop Price 80 cents<br/>&bull; Rule: Sell 50% on double <br/>&bull; 6% Trailing Stop Loss on stock<br/><br/><span style="font-weight:bold;">Volatility Analysis:</span><br/>&bull; <br/>&bull; <br/>&bull; <br/><br/><span style="font-weight:bold;">Techincal  Analysis:</span><br/>&bull; <br/>&bull; <br/>&bull; <br/><br/><span style="font-weight:bold;">Fundamental Analysis:</span><br/>&bull; <br/>&bull; <br/>&bull; <br/></span>',
           });

    var detailspanel = new Ext.Panel({
                fullscreen: true,
             padding:1,
             layout: {
                      type: 'vbox',
                      pack: 'center',
                      align: 'stretch'
                  },
                items: [showdetails]
             });
    });

上面的问题是,我尝试先运行代码,第二个警报正在发生并显示未定义.........

我的目标是解析数据并将其显示在面板中.

但我认为问题是,即使在商店完成操作之前,面板仍在显示,第一个警报正常工作并显示其中的值,但该操作在面板显示之后发生

请帮忙

谢谢 .....

Answer 1

您的Ext.data.Store正在通过异步请求加载到您的服务器.它不会阻止JavaScript的执行,因此它会发出请求,但不会等待数据返回,然后继续执行脚本的其余部分(即警报,面板等).

当商店加载时,它将触发事件'load'.当你举办这个活动时,那就是你想制作面板等的时候.

   Detailsstore.on('load', function() {
       // do everything here.
       // var showdetails = new Ext.Panel({ ...
       // var detailspanel = new Ext.Panel({ ...
    });
    Detailsstore.read(); // <-- fire off the request for data AFTER you set up your 'load' handler