Param0

Get a function's first parameter

Parameter of a function are often passed wrapped into an object, React props is a notable example:

function MyComponent(props: Props) {
	return <>...</>;
}

To extract Props you can use:

import type { Param0 } from "tsafe";

type props = Param0<typeof MyComponent>;

It's kind of the same of doing:

type props = Parameters<typeof MyComponent>[0];

but

declare function fun(): number;

type FunParams = Param0<typeof fun>;
//   ^void (instead of never)

and

declare function fun(params?: { foo: string }): void;

type FunParams = Param0<typeof fun>;
//   ^ { foo: string; } ( instead of { foo: string; } | undefined )