TypeScript Composables

Typing Composables

Annotate parameters and return types of composables for great DX.

Use generics for data-fetching helpers.

function useFetch<T>(url: MaybeRefOrGetter<string>) {
  const data = ref<T | null>(null)
  // ...
  return { data }
}

Generic fetch composable sketch.

MaybeRef

Accept Ref/getter/values via `toValue`.

• Handle loading and errors.
• Keep composables tested.
• Prefer TypeScript when you can.
• Measure before optimizing.

TypeScript Composables Cheatsheet

Quick reference for patterns covered in this lesson.

Public API

Export types next to composables used across packages.

Common Mistakes

• Implicit any returns.
• Overly wide object types.

Key Takeaways

• TypeScript Composables shows up often in Vue apps.
• Practice with a demo.
• Prefer clear APIs.
• Read official docs for edge cases.