Vue.js: How to type composables in Vue 3 with TypeScript?

1// composables/useCounter.ts
2import { ref, computed } from "vue"
3
4interface UseCounterOptions {
5    initialValue?: number
6    step?: number
7}
8
9interface UseCounterReturn {
10    count: Ref<number>
11    doubled: ComputedRef<number>
12    increment: () => void
13    decrement: () => void
14}
15
16export function useCounter(
17    options: UseCounterOptions = {}
18): UseCounterReturn {
19    const { initialValue = 0, step = 1 } = options
20    const count = ref(initialValue)
21    const doubled = computed(() => count.value * 2)
22    
23    function increment() {
24        count.value += step
25    }
26    
27    function decrement() {
28        count.value -= step
29    }
30    
31    return { count, doubled, increment, decrement }
32}