参考地址：https://developers.weixin.qq.com/community/develop/article/doc/000c86e3c9013032f68b5560d5b013

// app.js

onLaunch: function () {

    this.initObserve();

},

// 对globalData数据进行定向劫持。 

  initObserve() {

    const that = this;

    const obj = this.globalData;

    const keys = ['navHeight', 'hasLogin']; 

    keys.forEach(key => {

      that[`${key}SubscriberList`] = new Map();

      Object.defineProperty(obj, key, {

        configurable: true,

        enumerable: true,

        set(newValue) {

          that[`${key}SubscriberList`].forEach(watch => {

            watch(newValue);

          });

          obj[`_${key}`] = newValue;

        },

        get() {

          return obj[`_${key}`];

        }

      });

    });

  },

  // 根据页面实例订阅globalData中某个属性变化

  subscribe(key, watch, page) {

    watch(this.globalData[key]);

    this[`${key}SubscriberList`].set(page, watch);

  },

  // 取消订阅根据页面实例

  unsubscribe(key, page) {

    if (this[`${key}SubscriberList`].has(page)) {

      this[`${key}SubscriberList`].delete(page);

    }

  },

// 首页和我的page页

onLoad() {

    app.subscribe('navHeight', (navHeight) => {

        this.setData({

 navHeight,

        });

    },this);

},

onUnload(){

      getApp().unsubscribe('navHeight',this)

    }