#vue3 #TypeScript
`defineComponent`を使う。
```ts
<script lang="ts">
import { defineComponent } from "vue";
export default defineComponent({
data() {
return {
count: 0,
};
},
computed: {
doubleCount(): number {
return this.count * 2;
},
},
methods: {
incrementCount(): void {
this.count++;
},
},
});
</script>
<template>
<button @click="incrementCount">Count is: {{ count }}</button>
<div>Double: {{ doubleCount }}</div>
</template>
```
## 参考
[TypeScript with Options API | Vue.js](https://vuejs.org/guide/typescript/options-api.html)