Typing composables in Vue - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a composable in Vue 3?

A composable is a reusable function that uses Vue's Composition API to share reactive state and logic across components.

beginner

Why do we type composables in Vue with TypeScript?

Typing composables helps catch errors early, improves code completion, and makes the code easier to understand and maintain.

intermediate

How do you type the return value of a composable that returns a ref in Vue?

You specify the type inside the ref, for example: const count = ref<number>(0); and the composable returns { count } typed accordingly.

intermediate

What TypeScript utility type can help infer the return type of a composable function?

The ReturnType<T> utility type extracts the return type of a function type T, useful for typing composables.

intermediate

How can you type a composable that accepts parameters?

You define the parameter types explicitly in the function signature, for example: function useCounter(initial: number): { count: Ref<number> }.

What does a Vue composable typically return?

A CSS styles

B Reactive state and functions

C HTML templates

D Vue directives

Composables return reactive state and functions to share logic across components.

How do you type a ref holding a string in a Vue composable?

A ref<boolean>('')

B ref<number>('')

C ref<string>('')

D ref<any>('')

You specify the type inside ref, so ref('') creates a reactive string.

Which TypeScript feature helps infer the return type of a composable?

A ReturnType

B Partial

C Pick

D Readonly

ReturnType extracts the return type of a function, useful for composables.

Why is typing parameters in composables important?

A To generate HTML automatically

B To make the code run faster

C To add CSS styles

D To catch errors and improve code clarity

Typing parameters helps catch mistakes early and makes code easier to understand.

What is the main benefit of using composables in Vue?

A Reusing logic and state across components

B Writing inline CSS

C Creating new HTML tags

D Replacing Vue directives

Composables let you reuse logic and reactive state easily in multiple components.

Explain how to type a Vue composable that returns a reactive count and a function to increment it.

Think about typing the ref and the function inside the composable.

Describe why typing parameters and return values in composables improves Vue app development.

Consider benefits of TypeScript in general applied to composables.