Exploring the distinction between "() => void" and "() => {}" in programming

Exploring TS types, I defined the following:

type type1 = () => {}
type type2 = () => void

Then, I created variables using these types:

const customType1: type1 = () => { }
const customType2: type2 = () => { }

The issue surfaced as

"Type 'void' is not assignable to type '{}'"
for customType1. But why? Aren't both functions of type "void"?

Answer №1

type typeOne = () => {}
type typeTwo = () => void

The initial definition establishes a function type that produces {}, representing an empty object.

On the other hand, the second type denotes a function with a return type of void, meaning it returns nothing.


To correctly utilize the first type, ensure to enclose the {} within parentheses. Otherwise, TypeScript may interpret it as lacking a return statement.

const firstFunction: typeOne = () => ({})
const secondFunction: typeTwo = () => { }

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