typescript - 如何让函数传递具有相同重载的参数？

Question

我正在尝试创建一个函数，将它的参数传递给另一个函数。这两个函数都需要具有相同的重载。

function original (a: number): boolean;
function original (a: string, b: string): boolean;
function original (a: number | string, b?: string): boolean {
  return true;
}

function pass (a: number): boolean;
function pass (a: string, b: string): boolean;
function pass (a: number | string, b?: string): boolean {
  return original(a, b);
}

这不起作用。

Argument of type 'string | number' is not assignable to parameter of type 'string'.

Type 'number' is not assignable to type 'string'.(2345)input.tsx(4, 10): The call would have succeeded against this implementation, but implementation signatures of overloads are not externally visible.

Playground

Answer 1

转换到任何;)

function pass (a: number | string, b?: string): boolean {
    return original(a as any, b);

    // or if you have strictNullChecks: true - then b should also be casted.
    return original(a as any, b as any);
}

或者使用命名元组作为参数(效果类似于重载)。

function original(...args: [a: string, b: string] | [a: number]): boolean {
  return true;
}

function pass (...args: [a: string, b: string] | [a: number]): boolean {
  return original(...args);
}