微信小程序实现数据监听

Posted 2021-12-13 yangzhenhong

/**
 * 设置监听器watch.js
 */
export function setWatcher(page) {
  let data = page.data;
  let watch = page.watch;
  Object.keys(watch).forEach(v => {
    let key = v.split(‘.‘); // 将watch中的属性以‘.‘切分成数组
    let nowData = data; // 将data赋值给nowData
    for (let i = 0; i < key.length - 1; i++) { // 遍历key数组的元素，除了最后一个！
      nowData = nowData[key[i]]; // 将nowData指向它的key属性对象
    }
    let lastKey = key[key.length - 1];
    // 假设key===‘my.name‘,此时nowData===data[‘my‘]===data.my,lastKey===‘name‘
    let watchFun = watch[v].handler || watch[v]; // 兼容带handler和不带handler的两种写法
    let deep = watch[v].deep; // 若未设置deep,则为undefine
    observe(nowData, lastKey, watchFun, deep, page); // 监听nowData对象的lastKey
  })
}
/**
 * 监听属性 并执行监听函数
 */
function observe(obj, key, watchFun, deep, page) {
  var val = obj[key];
  // 判断deep是true 且 val不能为空 且 typeof val===‘object‘（数组内数值变化也需要深度监听）
  if (deep && val != null && typeof val === ‘object‘) {
    Object.keys(val).forEach(childKey => { // 遍历val对象下的每一个key
      observe(val, childKey, watchFun, deep, page); // 递归调用监听函数
    })
  }
  let that = this;
  Object.defineProperty(obj, key, {
    configurable: true,
    enumerable: true,
    set: function (value) {
      watchFun.call(page, value, val); // value是新值，val是旧值
      val = value;
      if (deep) { // 若是深度监听,重新监听该对象，以便监听其属性。
        observe(obj, key, watchFun, deep, page);
      }
    },
    get: function () {
      return val;
    }
  })
}
module.exports = {
  setWatcher: setWatcher
}

const watch = require("../../../utils/watch.js");

/**
   * 生命周期函数--监听页面加载
   */
  onLoad: function (options) {
    watch.setWatcher(this); // 设置监听器，建议在onLoad下调用
    // 取出登录信息
    this.getLOginInfo();
  },
  watch: {
    ‘prescriptionInfo.prescr_type‘: function (value, oldValue) {
      if (value == 0) {
        // console.log(‘中药处方‘);
        let bottled = ‘prescriptionInfo.is_bottled‘;
        let taste_type = ‘prescriptionInfo.taste_type‘;
        let is_pregnant = ‘prescriptionInfo.is_pregnant‘;
        let is_suffering = ‘prescriptionInfo.is_suffering‘;
        let suffering_num = ‘prescriptionInfo.suffering_num‘;
        this.setData({
          [bottled]: 0,
          [taste_type]: 1,
          [is_pregnant]: 0,
          [is_suffering]: 0,
          [suffering_num]: 1,
        });
      }
      if (value == 2) {
        // console.log(‘膏方‘);
        let is_pregnant = ‘prescriptionInfo.is_pregnant‘;
        let is_suffering = ‘prescriptionInfo.is_suffering‘;
        let suffering_num = ‘prescriptionInfo.suffering_num‘;
        this.setData({
          [is_pregnant]: 0,
          [is_suffering]: 0,
          [suffering_num]: 3,
        });
      }
    },
  },