Constructs a type consisting of the return type of function Type.

[nmsn]

Constructs a type consisting of the return type of function Type.

declare function f1(): { a: number; b: string };
type T0 = ReturnType<() => string>;
// type T0 = string

type T1 = ReturnType<(s: string) => void>;
// type T1 = void

type T2 = ReturnType<<T>() => T>;
// type T2 = unknown

type T3 = ReturnType<<T extends U, U extends number[]>() => T>;
//type T3 = number[]

type T4 = ReturnType<typeof f1>;
// type T4 = {
//     a: number;
//     b: string;
// }

type T5 = ReturnType<any>;     
// type T5 = any

type T6 = ReturnType<never>;
// type T6 = never

type T7 = ReturnType<string>;
// Type 'string' does not satisfy the constraint '(...args: any) => any'.
// type T7 = any

type T8 = ReturnType<Function>;
// Type 'Function' does not satisfy the constraint '(...args: any) => any'.
// Type 'Function' provides no match for the signature '(...args: any): any'.  
// type T8 = any

[nmsn]

/**
 * Obtain the return type of a function type
 */
type ReturnType<T extends (...args: any) => any> = T extends (...args: any) => infer R ? R : any;