1. 引入Vue的对象 ref , reactive, watch
   ref 用来声明响应式的基础类型的变量
   reactive用来声明响应式的对象类型的变量
   watch 引入watch对象，以便调用

import {ref, reactive, watch} from 'vue'

2. 声明一个数组变量

export default {
  setup(props){
	let infoList = reactive([
      {
        name:'张三',
        value: '24'
      },
      {
        name:'李四',
        value: '25'
      }
    ])
    return {
		infoList
	}
  }
}

3、绑定事件

<button @click="changeInfoList"></button>

4、改变数组的值

export default {
  setup(props){
	let infoList = reactive([
      {
        name:'张三',
        value: '24'
      },
      {
        name:'李四',
        value: '25'
      }
    ])
    function changeInfoList() {
		infoList[0].value = '26'
	}
    return {
		infoList,
		changeInfoList
	}
  }
}

4、watch监听变量

export default {
  setup(props){
	let infoList = reactive([
      {
        name:'张三',
        value: '24'
      },
      {
        name:'李四',
        value: '25'
      }
    ])
    function changeInfoList() {
		infoList[0].value = '26'
	}
	watch(infoList ,(newVal,oldVal)=> {
      console.log(newVal)
      }
    })
    return {
		infoList,
		changeInfoList
	}
  }
}

更新时间：2021/12/4
5. watch 加载页面就触发

watch(infoList ,(newVal,oldVal)=> {
      console.log(newVal)
      }
    },
    {immediate:true}
)