<template>
  <div>
    <button>是多少：{{count}}</button>
  </div>
</template>
<script>
import {reactive, toRefs, ref, watch} from 'vue'
export default {
  props: {
    select: Function,
  },
  setup(props, ctx) {
  // 定义数据源
  const count = ref(0);
  // 指定要监视的数据源
  watch(count, (count, prevCount) => {
    console.log(count, prevCount)
  })
  setInterval(() => {
    count.value += 2
  }, 2000)
  console.log(count.value)
  return {
    count
  }
}
}
</script>