vue3.0组合式api的使用小结

setup(){
  console.log('自动执行')
  const name = '林一'
  const age = 20
  const company = '阿里巴巴'
  
  const btn =  ()=>{
      const res = `我叫${name},今年${age}岁了,在${company}上班`
      console.log(res)
  }
 
  // 计算属性
  // 侦听器
  return {name,btn}
 }

import { onBeforeMount, ....... } from 'vue'

//安装
npm install vuex@next --save
//引入
import {useStore} from 'vuex'

import {toRef} from 'vue'
//toRef接收两个参数，第一个参数是要操作的对象，第二个参数是对象的某个属性
const obj = {name:'林一'}
toRef(obj,'name')

setup(){
     
    const obj = {name:'林一',age:40}
    //  const res = ref(obj.name)
    const res = toRef(obj,'name')
    const btn = ()=>{
         res.value = '林二'
         console.log(res)
         console.log(obj)
     }
    return {res,btn}
 }

import {ref} from 'vue'//组合式api
ref('林一')

setup(){
     const name = ref('林一')
     const age = ref(52)
     const company = ref('阿里巴巴')
    //  对象类型
     const obj = ref({
         taobao:'淘宝',
         tamll:'天猫'
     })
    //  数组类型
    const arr = ref([
        {
            xiami:'林二',
            huabei:'京东'
        }
    ])
     const btn = ()=>{
        //  响应对象类型
        //  name.value = '林三'
        //  obj.value.taobao = '淘宝000'
        //  console.log(obj)
        // 响应数组类型
        arr.value[0].xiami = '京东000'
        console.log(arr)
     }
     return {name,age,company,btn,obj,arr}
 }

//第一种：进入页面即刻传值（祖孙传值）
const p1 = reactive({name:'林一',age:52})
provide('p',p1)//祖传
 
const res = inject('p')//孙收
 
//第二种：点击传值
<Vue ref="val"/>//引入子组件，使用ref调用该子组件
const val = ref()
const p1 = reactive({name:'林一',age:52})
function btn(){
    val.value.receive(p1)
}

import { shallowReactive,shallowRef } from 'vue'

setup() {
        //shallowReactive:只处理第一层的数据
        const p1 = shallowReactive({
            name:'林一',
            product:{
                taobao:5
            }
        })
        // shallowRef:只处理基本类型数据
        const p2 = shallowRef({
            val:1
        })
        console.log(p2)
        return{...toRefs(p1),p2}
    },

import { watchEffect } from 'vue'

setup() {
        const p1 = ref(0)
        const p2 = ref(1)
        const p3 = reactive({
            name:'林一',
            age:50,
            product:{
                wx:14
            }
        })
       const S =  watchEffect(()=>{
            const a = p1.value
            const b = p2.value
            console.log('进入页面我就执行')
        })
        S()//停止监听
        return {p1,p2,p3}
    },

import { watch } from 'vue'

setup() {
        const p1 = ref(0)
        const p2 = ref(1)
        const p3 = reactive({
            name:'林一',
            age:50,
            product:{
                wx:14
            }
        })
        // 一：侦听ref的基本数据
        // watch(p1,(newVal,oldVal)=>{
        //     console.log(newVal,oldVal)
        // },{immediate:true})//{immediate:true}立即侦听
 
        // 二：侦听多个ref响应数据
        // watch([p1,p2],(newVal,oldVal)=>{
        //     console.log(newVal,oldVal)
        // })
 
        // 三：侦听整个reactive定义的数据:只能监听到最新的结果，之前的结果监听不到
        // watch(p3,(newVal,oldVal)=>{
        //     console.log(newVal,oldVal)
        // })
        
        // 四：侦听reactive定义的数据中的某一个值:可以监听到,无论层级有多深
        watch(()=>p3.product.wx,(newVal,oldVal)=>{
            console.log(newVal,oldVal)
        })
        return {p1,p2,p3}
    },

import { computed } from 'vue'

setup() {
 
    const mayun = ''
    const huateng = ''
    const res = reactive({linyi,liner})
 
    // 计算年龄总和
    const sum = computed({
        get(){
            return res.linyi + res.liner
        },
        set(val){
            console.log(val)
        }
    })
     
    return {...toRefs(res),sum}
}

import { reactive } from 'vue'
reactive({name:'林一'})

setup(){
    //  const name = reactive({name:'林一'})
    //  const age = reactive({age:20})
    //  const company = reactive({company:'阿里巴巴'})
    // //  深层次响应式
    //  const pro = reactive({
    //      a:'淘宝',
    //      b:'天猫',
    //      c:{
    //          d:'京东',
    //          e:'顺丰'
    //      }
    //  })
     const btn = ()=>{
    //    name.name = '林二'
    //    age.age = 40
    //    pro.c.d = '京东0000'
          res.name = '林三'
     }
    // 共用一个reactive
    const name = '林四'
    const age = 52
    const company = '阿里巴巴'
    const res = reactive({name,age,company})
 
 
     return {res,btn}
 }

import {toRefs} from 'vue'
toRefs(obj)

setup(){
    const obj = {name:'林一',age:40}
    const refs = reactive(obj)
    // const res = toRefs(refs)
     const btn = ()=>{
        //  res.name.value = '林三'
        //  console.log(res)
         console.log(refs)
         refs.name = '林二'
         console.log(refs)
         console.log(obj)
     }
     return {...toRefs(refs),btn}
 }