如果你想看一段时间的财产，然后取消它怎么办? 或者查看库子组件属性?

你可以使用“动态观察者”:

this.$watch(
 'object.property', //what you want to watch
 (newVal, oldVal) => {
    //execute your code here
 }
)

$watch返回一个unwatch函数，如果被调用，它将停止监视。

var unwatch = vm.$watch('a', cb)
// later, teardown the watcher
unwatch()

你也可以使用deep选项:

this.$watch(
'someObject', () => {
    //execute your code here
},
{ deep: true }
)

请一定要看一下医生

我对使用deep: true的公认答案的问题是，当深度观察一个数组时，我不能轻易地识别数组中的哪个元素包含了更改。我找到的唯一明确的解决方案是这个答案，它解释了如何制作一个组件，以便您可以单独观察每个数组元素。

https://vuejs.org/guide/essentials/watchers.html#deep-watchers

export default {
  watch: {
    someObject: {
      handler(newValue, oldValue) {
        // Note: `newValue` will be equal to `oldValue` here
        // on nested mutations as long as the object itself
        // hasn't been replaced.
      },
      deep: true
    }
  }
}

跟踪列表中单个更改的项

如果你想监视列表中的所有项目，并知道列表中的哪个项目发生了变化，你可以在每个项目上分别设置自定义监视器，如下所示:

var vm = new Vue({
  data: {
    list: [
      {name: 'obj1 to watch'},
      {name: 'obj2 to watch'},
    ],
  },
  methods: {
    handleChange (newVal, oldVal) {
      // Handle changes here!
      // NOTE: For mutated objects, newVal and oldVal will be identical.
      console.log(newVal);
    },
  },
  created () {
    this.list.forEach((val) => {
      this.$watch(() => val, this.handleChange, {deep: true});
    });
  },
});

如果你的列表没有立即填充(就像在最初的问题中)，你可以将逻辑从created移到任何需要的地方，例如在.then()块中。

观察不断变化的列表

如果你的列表本身更新到有新的或删除的项目，我已经开发了一个有用的模式，“浅层”观察列表本身，并动态观察/取消观察项目随着列表的变化:

// NOTE: This example uses Lodash (_.differenceBy and _.pull) to compare lists
//       and remove list items. The same result could be achieved with lots of
//       list.indexOf(...) if you need to avoid external libraries.

var vm = new Vue({
  data: {
    list: [
      {name: 'obj1 to watch'},
      {name: 'obj2 to watch'},
    ],
    watchTracker: [],
  },
  methods: {
    handleChange (newVal, oldVal) {
      // Handle changes here!
      console.log(newVal);
    },
    updateWatchers () {
      // Helper function for comparing list items to the "watchTracker".
      const getItem = (val) => val.item || val;

      // Items that aren't already watched: watch and add to watched list.
      _.differenceBy(this.list, this.watchTracker, getItem).forEach((item) => {
        const unwatch = this.$watch(() => item, this.handleChange, {deep: true});
        this.watchTracker.push({ item: item, unwatch: unwatch });
        // Uncomment below if adding a new item to the list should count as a "change".
        // this.handleChange(item);
      });

      // Items that no longer exist: unwatch and remove from the watched list.
      _.differenceBy(this.watchTracker, this.list, getItem).forEach((watchObj) => {
        watchObj.unwatch();
        _.pull(this.watchTracker, watchObj);
        // Optionally add any further cleanup in here for when items are removed.
      });
    },
  },
  watch: {
    list () {
      return this.updateWatchers();
    },
  },
  created () {
    return this.updateWatchers();
  },
});

这些答案对我来说都没用。实际上，如果你想观察嵌套的数据与组件被多次调用。所以他们被称为不同的道具来识别他们。 例如<MyComponent chart="chart1"/> <MyComponent chart="chart2"/> 我的解决方法是创建一个额外的vuex状态变量，我手动更新它以指向上次更新的属性。

这是一台Vuex。Ts实现示例:

export default new Vuex.Store({
    state: {
        hovEpacTduList: {},  // a json of arrays to be shared by different components, 
                             // for example  hovEpacTduList["chart1"]=[2,6,9]
        hovEpacTduListChangeForChart: "chart1"  // to watch for latest update, 
                                                // here to access "chart1" update 
   },
   mutations: {
        setHovEpacTduList: (state, payload) => {
            state.hovEpacTduListChangeForChart = payload.chart // we will watch hovEpacTduListChangeForChart
            state.hovEpacTduList[payload.chart] = payload.list // instead of hovEpacTduList, which vuex cannot watch
        },
}

在任何Component函数上更新存储:

    const payload = {chart:"chart1", list: [4,6,3]}
    this.$store.commit('setHovEpacTduList', payload);

现在对任何组件进行更新:

    computed: {
        hovEpacTduListChangeForChart() {
            return this.$store.state.hovEpacTduListChangeForChart;
        }
    },
    watch: {
        hovEpacTduListChangeForChart(chart) {
            if (chart === this.chart)  // the component was created with chart as a prop <MyComponent chart="chart1"/> 
                console.log("Update! for", chart, this.$store.state.hovEpacTduList[chart]);
        },
    },

我发现它也是这样运作的:

watch: {
    "details.position"(newValue, oldValue) {
        console.log("changes here")
    }
},
data() {
    return {
      details: {
          position: ""
      }
    }
}