Typescript关键字

infer

表示待推断的返回值类型
使用场景： 返回参数、返回值的类型

// 获取参数类型
type ConstructorParameters<T extends new (...args: any[]) => any> = T extends new (...args: infer P) => any
  ? P
  : never;

// 获取实例类型
type InstanceType<T extends new (...args: any[]) => any> = T extends new (...args: any[]) => infer R ? R : any;

class TestClass {
  constructor(public name: string, public age: number) {}
}

type Params = ConstructorParameters<typeof TestClass>; // [string, number]

type Instance = InstanceType<typeof TestClass>; // TestClass