8 - effectScope API（With explanations / 有解释）

[Hacker-C]

• the basic usage of effectScope API, you can learn it in vue3 docs effectScope. Be careful with the asynchronous, make sure scoped.top task is in asynchronous tasks queue with the task of the change of counter
• 注意处理 scope 的时机，由于 setTimeout 的回调是异步的，因此也要使得 scope.stop 放入异步队列中 counter 被修改 这个任务的后面。
• More: My solutions and explanations for vuejs challenges

App.vue:

<script setup lang="ts">
import { ref, computed, watch, watchEffect, effectScope } from 'vue'

const counter = ref(1)

// use the `effectScope` API to make these effects stop together after being triggered once

const scope = effectScope()

scope.run(() => {
  const doubled = computed(() => counter.value * 2)
  watch(doubled, () => console.log(doubled.value))
  watchEffect(() => console.log(`Count: ${doubled.value}`))
})

counter.value = 2

// this is also right:
// setTimeout(() => {
//   scope.stop()
// })

setTimeout(() => {
  counter.value = 4
  scope.stop()
  // be careful with the asynchronous, make sure `scoped.top` task is in asynchronous tasks queue with the task of `the change of counter`
  // 注意处理 scope 的时机，由于 setTimeout 的回调是异步的，因此也要使得 scope.stop 放入异步队列中 `counter 被修改` 这个任务的后面。
})
</script>

<template>
  <div>
    <p>
      <!-- {{ doubled }} -->
    </p>
  </div>
</template>

[JJczC-love]

你的解释不对，应该是watch和watchEffect是耗时的，所以stop的时间窗口是第一次counter改变导致监听回调触发到第二次counter值改变导致的监听回调触发；