vue3中的ref和reactive定义数组方式

import { ref } from 'vue'
const arr = ref([])

import { ref,watch } from 'vue'
const arr = ref([1，2，3])
watch(arr.value, () => { //这个时候通过直接修改和利用数组的方法修改都可以监测到
  console.log('数组变化了')
})
const pushArray = () => {
  emptyArray.value.splice(0, 0, 19)
}
const changeArrayItem = () => {
  emptyArray.value[0] = 10
}

import { ref,watch,onMounted } from 'vue'
const arr = ref([])
watch( //这个时候不能用.value且必须是深度监听，这种写法不仅可以监听数组本身的变化，也可以监听 数组元素的变化
  arr,
  () => {
    console.log('空数组变化了')
  },
  {
    deep: true
  }
)
const pushArray = () => {
  arr.value.splice(0, 0, { value: 12 })
}
const changeArrayItem = () => {
  arr.value[0] = { value: 32 }
}
onMounted(() => {
  arr.value = [{ value: 5 }, { value: 2 }, { value: 3 }, { value: 4 }]
})

import { reactive } from 'vue';
let arr = reactive([])
function change(){
   let newArr = [1,2,3]
   arr = newArr
}

import { reactive,ref } from 'vue';
let arr = reactive([])
function change(){
   let newArr = [1,2,3]
   arr = newArr
}
// 方法一：使用 ref
let arr = ref([])
function change(){
   let newArr = [1,2,3]
   arr.value = newArr
}
// 方法二：使用push 方法
let arr = reactive([])
function change(){
   let newArr = [1,2,3]
   arr.push(...newArr)
}
// 方法三：外层嵌套一个对象
let arr = reactive({list:[]})
function change(){
   let newArr = [1,2,3]
   arr.list = newArr
}