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

import { ref,watch } from 'vue'
const arr = ref([1，2，3])
watch(arr.value, () => { //這個(gè)時(shí)候通過直接修改和利用數(shù)組的方法修改都可以監(jiān)測到
  console.log('數(shù)組變化了')
})
const pushArray = () => {
  emptyArray.value.splice(0, 0, 19)
}
const changeArrayItem = () => {
  emptyArray.value[0] = 10
}

import { ref,watch,onMounted } from 'vue'
const arr = ref([])
watch( //這個(gè)時(shí)候不能用.value且必須是深度監(jiān)聽，這種寫法不僅可以監(jiān)聽數(shù)組本身的變化，也可以監(jiān)聽 數(shù)組元素的變化
  arr,
  () => {
    console.log('空數(shù)組變化了')
  },
  {
    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：外層嵌套一個(gè)對象
let arr = reactive({list:[]})
function change(){
   let newArr = [1,2,3]
   arr.list = newArr
}