CODEWITHSUNDEEP
typescript
Johnny Copperstone
Johnny Copperstone

Reputation: 793

Type a function declaration

Given this type definition

type MyFunction = (prop: string) => boolean

I know it's possible to type an anonymous function

const myFunction: MyFunction = (prop) => true

But I'm not sure on how to do this for a regular function definition

function myFunction (prop) {
  return true;
}

Is this possible, and if so how? Thanks

EDIT

Just to clarify, I'm looking for a way to type the function using the same type definition, and not broken down inside the function, if it's at all possible. The main reason is to be able to re-use the type definition in other places.. callbacks, declaration files etc

Upvotes: 2

Views: 71

Answers (1)

Pavel Lint
Pavel Lint

Reputation: 3527

Like this

function myFunction (prop: string) : boolean {
  return true;
}

EDIT If you want to make a reusable function type, then you have to create your functions as variables, i.e. const myFunc: FuncType = function(param: string) : boolean { ... }. You can't do that with declarative function () syntax without creating a variable.

Upvotes: 2

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