// 总价

        var totalNum = '0.00';   //总价初始值

        var $total = new Ext.form.Label({

            text: '消费金额  : ￥' + totalNum + '元',

            name: 'total',

            margin: '0 0 0 44'

        });

        //购买数量form

        var $buyNum = new Ext.form.TextField({

            xtype: 'textfield',

            width: 200,

            labelWidth: 60,

            fieldLabel: '购买数量',

            value: '单位(个)',

            margin: '5 0 10 45',

            fieldStyle: 'color:gray',

            enableKeyEvents: true,

            listeners: {

                focus: function () {

                    this.setValue("");

                },

                change: function (pthis, newValue, oldValue, eOpts ){

                    totalNum = (newValue * 0.2).toFixed(2);

                    //验证输入数字

                    if (/^[0-9]*$/.test(newValue) === true) {

                        $total.setConfig('text', '消费金额：￥' + totalNum + '元');

                    } else {

                        newValue = 0;

                    }

                }

            }

        });

//  创建内容

        var $label = [{

            xtype: 'label',

            text: '当前可用余额 :' + "￥200元',

            margin: '10 0 0 41'

        }, {

            xtype: 'tbtext',

            margin: '10 0 0 40',

            text: '单价 : 0.2元/个'     //可以拼接使动态给值

        }, $buyNum, $total];

// 创建窗口

        var win = Ext.create('Ext.window.Window', {

            title: '购买商品',

            width: 300,

            height: 200,

            layout: 'vbox',

            modal: true,

            plain: true,

            items: $label,

            buttons: [{

                text: '确定'

            }, {

                text: '取消',

                handler: function () {

                    win.close();

                }

            }]

        });

        win.show();