question 1: 
 the wepy document says that in the Page page instance, the App instance can be accessed through this.$parent. What should I do if I want to access an app instance in a js? 
wepy.login({
  success: function({ code }) { 
    ajax("user/login", {
      code
    }).then(res => {
      if (res) {
        wx.setStorageSync("user_id", res.user_id)
        wx.setStorageSync("auth_token", res.auth_token)
      }
      // res.store_id  res.store_nameapp.globalData
      getDefaultStore().then(res => {
        fn()
      })
    })
  }
})
 question 2: 
 wepy document says: 
 / / how to use WePY, you need to enable Promise support. Refer to the development specification section 
 wepy.request ("xxxx"). Then ((d) = > console.log (d)); 
 1). How to enable Promise support? 
 2. Can all native Wechat api be called in the way of wepy.apiName. For example, wx.login can use wepy.login, wx.setNavigationBarTitle can use wepy.setNavigationBarTitle 
