构造函数参数类型

构造函数参数类型 ConstructorParameters<T>

class User {
  constructor(public name: string, public age: number) {}
}
type MyConstructorParameters<T extends abstract new (...args: any) => any> =
  T extends abstract new (...args: infer P) => any ? P : never;
// 构造函数参数类型
type userContructorType = ConstructorParameters<typeof User>; // [name: string, age: number]

/**
 *
 */
class Book {
  title: string;
  content: string;
  constructor(title: string, content: string) {
    this.title = title;
    this.content = content;
  }
}

class CreateInstance<T extends new (...args: any) => any> {
  private instanceConstructor: T;
  constructor(classConstructor: T) {
    this.instanceConstructor = classConstructor;
  }
  getInstance(...args: ConstructorParameters<T>): InstanceType<T> {
    return this.instanceConstructor(...args);
  }
}

const book = new CreateInstance(Book);
book.getInstance("title", "content"); // Book { title: 'title', content: 'content' }

实例对象类型 InstanceType<T>

class Book {
  title: string;
  content: string;
  constructor(title: string, content: string) {
    this.title = title;
    this.content = content;
  }
}

type instanceType = InstanceType<typeof Book>; // Book

获取异步接口返回的 Promise 类型的泛型 Awaited<T>

interface User {
  name: string;
  age: number;
  address: string;
}

async function getUser(): Promise<User> {
  const data = await fetch("https://jsonplaceholder.typicode.com/users/1");
  return data.json();
}

type UserType = Awaited<ReturnType<typeof getUser>>; // User{ name: string; age: number; address: string; }
const user: UserType = {
  name: "John",
  age: 30,
  address: "New York",
};