Counter.vue

<template>
	<div id="vue" class="counter">
		<button @click="subtract()">-</button>
		<pre>{{ count }}</pre>
		<button @click="add()">+</button>
	</div>
</template>

<script>
import { ref } from 'vue';
export default {
	setup() {
		const count = ref(0);
		const add = () => (count.value = count.value + 1);
		const subtract = () => (count.value = count.value - 1);

		return {
			count,
			add,
			subtract,
		};
	},
};
</script>