Sencha touch ——Ext.get()

Ext.application({
    name:'myApp',
    launch:function(){
      var panel=new Ext.Panel({
                    id:'mypanel',
                    html:'一个简单的事例面板'
        });
        Ext.get('mypanel').addCls('colorRed');
        Ext.Viewport.add(panel);
    }
});