vue3基础之watch监听

watch监听基本使用

• watch是一个函数,需要引入使用,监听多个数据只要多次调用watch函数即可
• watch第一个参数是监听的数据
• watch第二个参数是监听后的回调函数,参数为newVal和oldVal
• watch第三个参数是配置对象,包含immediate和deep

watch监听ref基本类型数据

• 直接监听即可,不用设置deep深度监听

<template>
  <div>watch监听</div><br/>
  <div @click="count++" style="cursor: pointer;">点击增加: {{count}}</div>
</template>

<script lang="ts">
import {defineComponent} from "vue";
export default defineComponent({
  name: "WatchPra"
})
</script>
<script setup lang="ts">
import {ref,watch} from 'vue';
let count  = ref<number>(0);
watch(count,(newVal,oldVal)=>{
  console.log('监听到数据:',newVal,oldVal)
},{immediate:true})
</script>

watch监听ref复杂类型数据

• 直接监听ref对象,只能监听到当前ref对象的值被替换
• 如果想监听ref代理对象的改变,则需要设置deep进行深度监听
• 直接监听ref对象的value值,会默认开启深度监听
• 监听ref代理对象内部的某个属性值,值是复杂数据类型时,默认开启深度监听,如果参数一使用函数式写法,不会默认开启深度监听
• 监听ref对象内部某个属性值,值是基本数据类型时,写法参数一使用函数式写法,默认开启深度监听

<template>
  <div>watch监听</div><br/>
<!--  <div @click="count++" style="cursor: pointer;">点击增加: {{count}}</div>-->
  <div @click="cat.age++" style="cursor: pointer;">点击增加: {{cat}}</div>
</template>

<script lang="ts">
import {defineComponent} from "vue";
export default defineComponent({
  name: "WatchPra"
})
</script>
<script setup lang="ts">
import {ref,watch} from 'vue';
// let count  = ref(0);
// watch(count,(newVal,oldVal)=>{
//   console.log('监听到数据:',newVal,oldVal)
// },{immediate:true})
let cat = ref<object>({name:'小五',age:3,color:'orange'})
watch(cat,(newVal,oldVal)=>{
  console.log('监听到变化: ', {cat})
})
</script>

<template>
  <div>watch监听</div><br/>
<!--  <div @click="count++" style="cursor: pointer;">点击增加: {{count}}</div>-->
  <div @click="cat.age++" style="cursor: pointer;">点击增加: {{cat}}</div>
  <div @click="cat={name:'小五',age:3,color:'white'}" style="cursor: pointer;">点击替换: {{cat}}</div>
</template>

<script lang="ts">
import {defineComponent} from "vue";
export default defineComponent({
  name: "WatchPra"
})
</script>
<script setup lang="ts">
import {ref,watch} from 'vue';
// let count  = ref(0);
// watch(count,(newVal,oldVal)=>{
//   console.log('监听到数据:',newVal,oldVal)
// },{immediate:true})
let cat = ref<object>({name:'小五',age:3,color:'orange'})
watch(cat,(newVal,oldVal)=>{
  console.log('监听到变化: ', {cat})
})
</script>

<template>
  <div>watch监听</div><br/>
<!--  <div @click="count++" style="cursor: pointer;">点击增加: {{count}}</div>-->
<!--  <div @click="cat.age++" style="cursor: pointer;">点击增加: {{cat}}</div>-->
<!--  <div @click="cat={name:'小五',age:3,color:'white'}" style="cursor: pointer;">点击替换: {{cat}}</div>-->
  <div @click="cat.active.push('抓老鼠')" style="cursor: pointer;">点击添加数据: {{cat}}</div>
</template>

<script lang="ts">
import {defineComponent} from "vue";
export default defineComponent({
  name: "WatchPra"
})
</script>
<script setup lang="ts">
import {ref,watch} from 'vue';
// let count  = ref(0);
// watch(count,(newVal,oldVal)=>{
//   console.log('监听到数据:',newVal,oldVal)
// },{immediate:true})
// let cat = ref