小程序如何获取手机号信息

<button open-type="getPhoneNumber" bindgetphonenumber="getPhoneNumber">
   手机号领取
</button>

 getPhoneNumber(e) {
    var msg = e.detail.errMsg, that = this;
    var that = this;
    var sessionID=that.data.userinfo.Session_key,
    encryptedDataStr=e.detail.encryptedData,
    iv= e.detail.iv;
    if (msg == 'getPhoneNumber:ok') {
      wx.checkSession({
        success:function(){
          that.deciyption(sessionID,encryptedDataStr,iv);
        },
        fail:function(){
          wx.login({
            success: res => {
              console.log(res,'sessionkey过期')
              wx.request('url',{code:res.code},function(res){
                var userinfo=res.data.data;
                wx.setStorageSync('userinfo',userinfo);
                that.setData({
                  userinfo:userinfo
                });
                that.deciyption(userinfo.Session_key,encryptedDataStr,iv);
              })
            }
          })
        }
      })
    }
  },
 deciyption(sessionID,encryptedDataStr,iv){
    wx.request('url', {
      sessionID: sessionID,
      encryptedDataStr:encryptedDataStr,
      iv: iv
    }, function (res) {
    //这个res即可返回用户的手机号码
    })
  },