wx.login({
  success (res) {
    if (res.code) {
      //发起网络请求
      wx.request({
        url: 'https://example.com/onLogin',
        data: {
          code: res.code
        }
      })
    } else {
      console.log('登录失败!' + res.errMsg)
    }
  }
})GET https://api.weixin.qq.com/sns/jscode2session?appid=APPID&secret=SECRET&js_code=JSCODE&grant_type=authorization_code