微信小程序从缓存里获取信息提示that is not defined.

微信小程序从缓存里获取信息提示that is not defined.
我想要获取登录信息,准备从缓存里获取openId.

但是却报错了.

that.setData改成this.setData

that改成this

你这个that哪来的