打字稿强制函数接受第一个参数

Question

我想强制特定函数接受特定类型的第一个参数

type MyFunc = <Args extends []>(channelId: string, ...args: Args) => string

const doThing: MyFunc = (channelId: string, arg1: number, arg2: string) => arg1 + arg2

我收到以下错误

Type '(channelId: string, arg1: number, arg2: string) => string' is not assignable to type 'MyFunc'.
  Types of parameters 'arg1' and 'args' are incompatible.
    Type 'Args' is not assignable to type '[arg1: number, arg2: string]'.
      Type '[]' is not assignable to type '[arg1: number, arg2: string]'.
        Source has 0 element(s) but target requires 2.

Playground link

Answer 1

你会这样做，但是......

您确定要连接数字和字符串（并且不使用channelId 参数）吗？

TS Playground

type MyFunc<Params extends readonly unknown[]> = (channelId: string, ...params: Params) => string;

const doThing: MyFunc<[n: number, str: string]> = (channelId, arg1, arg2) => arg1 + arg2;

const result = doThing('my_channel_id', 42, 'hello world');
console.log(result) // "42hello world"