extjs报错variety.js:2 Uncaught TypeError: Ext.define is not a function at variety.js:2

Question

Ext.define('exploit.hello.variety',{ extend: 'Ext.panel.Panel', title: "west",    layout: "accordion",  //设置为手风琴布局    layoutConfig: {        animate: true    },    width: 250,    minWidth: 90,    region: "west", //设置方位    split: true,    collapsible: true,    items: [                { title: "嵌套面板一", html: "嵌套面板一", iconCls: "save" },                { title: "嵌套面板二", html: "嵌套面板二", iconCls: "search" },                { title: "嵌套面板三", html: "嵌套面板三", iconCls: "back" },                { title: "嵌套面板四", html: "嵌套面板四", iconCls: "12" }           ]});