<script setup>
import { ref,computed } from 'vue'
const num = ref(1)
//computed返回一個只讀響應式ref對象computedNum
//computedNum是只讀屬性
let computedNum = computed(() => num.value + 1)
</script>
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<template>
    <p> num:{{ num }} </p>
    <p>computedNum:{{ computedNum }}</p>
    <!-- 修改響應式變量num 觸發(fā)與之綁定的computed的getter-->  
    <button @click="num++">num++</button>
    <!-- computedNum是只讀屬性-->  
    <button @click="computedNum++">computedNum++</button>
</template>

<script setup>
import { ref, computed } from 'vue'
const num = ref(1)
//getter（只讀）
let computedNum = computed(() => num.value + 1)
//getter和setter （可讀可寫）
let computedNum2 = computed({
    get: () => num.value + 1,
    set: (val) => {
         console.log(val);
        //setter中修改ref響應式變量num，將觸發(fā)關聯(lián)的num的getter計算
        //computedNum和computedNum2的getter同時觸發(fā)
         num.value++
          }
})
</script>
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<template>
    <p> num:{{ num }} </p>
    <p>computedNum:{{ computedNum }}</p>
    <p>computedNum2:{{ computedNum2 }}</p>
    <button @click="num++">num++</button>
    <!-- computedNum是只讀屬性，會有警告提醒 Write operation failed: computed value is readonly-->  
    <button @click="computedNum++">computedNum++</button>
     <!-- computedNum2是可讀可寫屬性-->  
    <button @click="computedNum2++">computedNum2++</button>
</template>

<script setup>
import { ref, computed } from 'vue'
const num = ref(1)
let computedNum = computed(() => num.value + 1, {
    onTrack: (e) => {
        console.log('onTrack');
        console.log(e);
    },
    onTrigger: (e) => {
        console.log('onTrigger');
        console.log(e);
    }
})
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</script>
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<template>
    <p> num:{{ num }} </p>
    <p>computedNum:{{ computedNum }}</p>
    <!--每次 num++將觸發(fā)onTrigger -->
    <button @click="num++">num++</button>
</template>

<script setup>
import { ref, watchEffect } from 'vue'
const num = ref(1)
//會立即執(zhí)行一次
watchEffect(() => {
    console.log('watchEffect');
    num.value++
})
</script>
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<template>
    <p>num: {{ num }}</p>
    <button @click="num++">num++</button>
</template>

const stop = watchEffect(() => {
  /* ... */
})
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// 顯式停止
stop()

import { ref, watchEffect } from 'vue'
const num = ref(1)
watchEffect((onInvalidate ) => {
    console.log('watchEffect-1');
    num.value++
    onInvalidate (()=>{
        console.log('onInvalidate-2');
    })
    console.log('watchEffect-3');
})
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//1、watchEffect   被重新觸發(fā)時
// onInvalidate-2
// watchEffect-1
// watchEffect-3
//2、組件卸載時
// onInvalidate-2
//3、關聯(lián)的響應式數(shù)據(jù)首次被修改（組件被掛載時）
//  watchEffect-1
//  watchEffect-3

//推遲觸發(fā)watchEffect
watchEffect(
  () => {
    /* ... */
  },
  {
    flush: 'post'
  }
)
//Vue3.2語法糖watchPostEffect
watchPostEffect(()=>{
  /* ... */
})

//實驗watchEffect第二參數(shù) flush: 'post'屬性
watchEffect(() => {
    console.log("實驗watchEffect第二參數(shù) {flush: 'post'}屬性");
    console.log(obj.age);
},{
   flush:'post' 
})
watchEffect(() => {
    console.log("watchEffect正常時機觸發(fā)");
    console.log(obj.age);
})
//生命周期onUpdated
onUpdated(()=>{
    console.log('onUpdated()');  
})
//生命周期onBeforeUpdate
onBeforeUpdate(()=>{
    console.log('onBeforeUpdate()');
})

watchEffect(
  () => {
    /* ... */
},
  {
    flush: 'sync'
  }
)
//Vue3.2語法糖watchSyncEffect
watchSyncEffect(()=>{
  /* ... */
})

//假設修改了對象的屬性值-修改了obj.age
const obj = reactive({ name: '小明', age: 18 })
//watchEffect不能監(jiān)聽對象變化
watchEffect(() => {
    console.log('watchEffect監(jiān)聽對象變化');
    console.log(obj);
})
//watchEffect可以監(jiān)聽對象屬性變化
watchEffect(() => {
    console.log('watchEffect監(jiān)聽對象屬性變化');
    console.log(obj.age);
})
//watch監(jiān)聽對象變化
watch(obj, (obj) => {
    console.log('watch監(jiān)聽對象變化');
    console.log(obj);
})

// 偵聽一個 getter
//被監(jiān)聽數(shù)據(jù)傳入一個帶返回值的回調(diào)函數(shù)
const state = reactive({ count: 0 })
watch(
  () => state.count,
  (count, prevCount) => {
    /* ... */
  }
)
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// 直接偵聽一個 ref
const count = ref(0)
watch(count, (count, prevCount) => {
  /* ... */
})

watch([fooRef, barRef], ([foo, bar], [prevFoo, prevBar]) => {
  /* ... */
})

// 只讀的
function computed<T>(
  getter: () => T,
  debuggerOptions?: DebuggerOptions
): Readonly<Ref<Readonly<T>>>
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// 可寫的
function computed<T>(
  options: {
    get: () => T
    set: (value: T) => void
  },
  debuggerOptions?: DebuggerOptions
): Ref<T>
interface DebuggerOptions {
  onTrack?: (event: DebuggerEvent) => void
  onTrigger?: (event: DebuggerEvent) => void
}
interface DebuggerEvent {
  effect: ReactiveEffect
  target: any
  type: OperationTypes
  key: string | symbol | undefined
}

function watchEffect(
  effect: (onInvalidate: InvalidateCbRegistrator) => void,
  options?: WatchEffectOptions
): StopHandle
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interface WatchEffectOptions {
  flush?: 'pre' | 'post' | 'sync' // 默認：'pre'
  onTrack?: (event: DebuggerEvent) => void
  onTrigger?: (event: DebuggerEvent) => void
}
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interface DebuggerEvent {
  effect: ReactiveEffect
  target: any
  type: OperationTypes
  key: string | symbol | undefined
}
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type InvalidateCbRegistrator = (invalidate: () => void) => void
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type StopHandle = () => void

// 偵聽單一源
function watch<T>(
  source: WatcherSource<T>,
  callback: (
    value: T,
    oldValue: T,
    onInvalidate: InvalidateCbRegistrator
  ) => void,
  options?: WatchOptions
): StopHandle
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// 偵聽多個源
function watch<T extends WatcherSource<unknown>[]>(
  sources: T
  callback: (
    values: MapSources<T>,
    oldValues: MapSources<T>,
    onInvalidate: InvalidateCbRegistrator
  ) => void,
  options? : WatchOptions
): StopHandle
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type WatcherSource<T> = Ref<T> | (() => T)
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type MapSources<T> = {
  [K in keyof T]: T[K] extends WatcherSource<infer V> ? V : never
}
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// 參見 `watchEffect` 共享選項的類型聲明
interface WatchOptions extends WatchEffectOptions {
  immediate?: boolean // 默認：false
  deep?: boolean
}