wx.getextconfig 获取不到数据

if (wx.getExtConfig) {

wx.getExtConfig({

success: function (res) {

extConfig = res.extConfig;

console.log(res)

},

fail:function(e){

console.log(e)

}

})

getApp().globalData.extMid = extConfig.mid;

getApp().globalData.appid = extConfig.appid;

}