5 - watch 全家桶

[wushirenfeiH]

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

const count = ref(0)

/**
 * Challenge 1: Watch once
 * Make sure the watch callback only triggers once
*/
const unWatch = watch(count, () => {
  console.log("Only triggered once")
  unWatch()
})

count.value = 1

setTimeout(() => count.value = 2)

/**
 * Challenge 2: Watch object
 * Make sure the watch callback is triggered
*/
const state = ref({
  count: 0,
})

watch(state, () => {
  console.log("The state.count updated")
}, {
  deep: true
})

state.value.count = 2

/**
 * Challenge 3: Callback Flush Timing
 * Make sure visited the updated eleRef
*/

const eleRef = ref()
const age = ref(2)
watch(age, () => {
  console.log(eleRef.value)
}, {
  flush: 'post'
})
age.value = 18

</script>

<template>
  <div>
    <p>
      {{ count }}
    </p>
    <p ref="eleRef">
      {{ age }}
    </p>
  </div>
</template>