TS入门篇 | 详解 TypeScript 类类型（下）

class UserInfo {
  readonly name: string;
  constructor(name: string) {
    this.name = name;
  }
}
const user = new UserInfo("TypeScript");
user.name = "haha"; // error Cannot assign to 'name' because it is a read-only property
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class A {
  constructor(name: string) {}
}
const a = new A("aaa");
console.log(a.name); // error 类型“A”上不存在属性“name”
class B {
  constructor(public name: string) {}
}
const b = new B("bbb");
console.log(b.name); // "bbb"
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class Parent {
  public static age: number = 18;
  public static getAge() {
    return Parent.age;
  }
  constructor() {
    //
  }
}
const p = new Parent();
console.log(p.age); // error Property 'age' is a static member of type 'Parent'
console.log(Parent.age); // 18
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class Parent {
  public static getAge() {
    return Parent.age;
  }
  private static age: number = 18;
  constructor() {
    //
  }
}
const p = new Parent();
console.log(p.age); // error Property 'age' is a static member of type 'Parent'
console.log(Parent.age); // error 属性“age”为私有属性，只能在类“Parent”中访问。
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class Info {
  name: string;
  age?: number;
  constructor(name: string, age?: number, public sex?: string) {
    this.name = name;
    this.age = age;
  }
}
const info1 = new Info("TypeScript");
const info2 = new Info("TypeScript", 18);
const info3 = new Info("TypeScript", 18, "man");
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class People {
  constructor(public name: string) {}
}
let people: People = new People("TypeScript");
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class Animal {
  constructor(public name: string) {}
}
let people = new Animal("JavaScript");
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abstract class People {
  constructor(public name: string) {}
  abstract printName(): void;
}
class Man extends People {
  constructor(name: string) {
    super(name);
    this.name = name;
  }
  printName() {
    console.log(this.name);
  }
}
const m = new Man(); // error Expected 1 arguments, but got 0.
const man = new Man("TypeScript");
man.printName(); // 'TypeScript'
const p = new People("TypeScript"); // error Cannot create an instance of an abstract class.
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abstract class People {
  constructor(public name: string) {}
  abstract printName(): void;
}
class Man extends People {  // error Non-abstract class 'Man' does not implement inherited abstract member 'printName' from class 'People'
  constructor(name: string) {
    super(name);
    this.name = name;
  }
}
const m = new Man("TypeScript");
m.printName(); // error m.printName is not a function
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abstract class People {
  abstract name: string;
  abstract get insideName(): string;
  abstract set insideName(value: string);
}
class Pp extends People {
  name: string;
  insideName: string;
}
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class UserInfo {
  private name: string;
  constructor() {}
  get userName() {
    return this.name;
  }
  set userName(value) {
    console.log(`setter: ${value}`);
    this.name = value;
  }
}
const user = new UserInfo();
user.name = "TypeScript"; // "setter: TypeScript"
console.log(user.name); // "TypeScript"
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interface FoodInterface {
  type: string;
}
class FoodClass implements FoodInterface {
  // error Property 'type' is missing in type 'FoodClass' but required in type 'FoodInterface'
  static type: string;
  constructor() {}
}
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interface FoodInterface {
  type: string;
}
class FoodClass implements FoodInterface {
  constructor(public type: string) {}
}
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abstract class FoodAbstractClass {
  abstract type: string;
}
class Food extends FoodAbstractClass {
  constructor(public type: string) {
    super();
  }
}
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class A {
  protected name: string;
}
interface I extends A {}
class B implements I {} // error Property 'name' is missing in type 'B' but required in type 'I'
class C implements I {
  // error 属性“name”受保护，但类型“C”并不是从“A”派生的类
  name: string;
}
class D extends A implements I {
  getName() {
    return this.name;
  }
}
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const create = <T>(c: { new (): T }): T => {
  return new c();
};
class Info {
  age: number;
}
create(Info).age;
create(Info).name; // error 类型“Info”上不存在属性“name”
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