Test.vue

<template>
  <div>Data: {{ data }}</div>
  <button @mousedown="method"></button>
</template>
<script lang="ts" setup>
  import { computed, ref } from 'vue'

  const test = ref(100)
  const data = computed(() => test.value + 200)

  const method = () => {
    return test
  }
</script>
<style></style>