TypeScript - type of function with variable number of parameters

Question

I would like to create a type called OnClick that accepts a variable number of types as arguments. How would I go about to make this work? I want to be able to use parameters of different types.

type OnClick<..> = (..) => void;

// usage:
const onClick: OnClick<string, number> = (key, value) => {...}
const onClick2: OnClick<SomeType, AnotherType> = (someThing, anotherThing) => {...}

typescriptlang.org/docs/handbook/functions.html#overloads

CRice
– CRice

2020-10-29 14:27:51 +00:00
Commented Oct 29, 2020 at 14:27 — CRice
– CRice, Commented Oct 29, 2020 at 14:27

Николай Гольцев · Accepted Answer · 2020-10-29 14:29:47Z

2

You can use constraint to T to declare it as tuple and then use it to type args:

type OnClick<T extends any[]> = (...args: T) => void;

// usage:
const onClick: OnClick<[string, number]> = (key, value) => {}

answered Oct 29, 2020 at 14:29

Николай Гольцев

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3 Comments

Amsvartner Over a year ago

Is there any way to do this without having to specify types in an array?

Николай Гольцев Over a year ago

I think no. Even the suggested solution is an workaround.

webpreneur Over a year ago

What would you prefer instead of the tuple?

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