Generic Decorator

decorate.ts

type Fn = (...args: any) => any
type Awaited<T> = T extends PromiseLike<infer U> ? U : T

export function someDecorator<V extends Fn>(method: V) {
  // Do some initialization logic here

  return async function (...args: Parameters<V>): Promise<Awaited<ReturnType<V>>> {
    // Do some args manipulation or validation

    const value = await method(...args)
    // Do some value manipulation or validation

    return value
  }
}

async function someAsyncMethod(a: string, b: string) {
  return { a, b }
}

const someDecoratedAsyncMethod = someDecorator(someAsyncMethod)

someDecoratedAsyncMethod('foo', 'bar')