private、public、protected、readonly、static

1、默认是public

自由的访问程序里定义的成员

class Parent {
  public name: string;
  constructor(theName: string) {
    this.name = theName;
  }
}
let a = new Parent("张三").name;

2、private

私有，不能在声明它的类的外部访问，如下

class Parent {
  private name: string;
  constructor(theName: string) {
    this.name = theName;
  }
}
let a = new Parent("张三").name; //属性"name"为私有属性，只能在类"Parent"中访问。

3、protected

受保护成员只能在类及其子类中访问，而不能在类的实例中访问

class Parent {
  protected name: string;
  constructor(theName: string) {
    this.name = theName;
  }
}
let a = new Parent("张三").name;//属性"name"受保护，只能在类"Super及其子类中访问"

class Parent {
  protected name: string;
  constructor(theName: string) {
    this.name = theName;
  }
}
// let a = new Parent("张三").name;
class Cat extends Parent {
  constructor(theName: string) {
    super(theName);
    this.name = '张三,'
  }
}

4、readonly修饰符

class Octopsus {
    readonly name: string;
    readonly numberOfLegs: string;
    constructor(theName: string) {
        this.name = theName
    }
}
let dad = new Octopsus('张三');
dad.name = "修改值" //无法分配到"name"，因为它是只读属性。

5、static

类的静态成员只能通过类名来调用，二不能通过子类调用

class Octopus {
    public name: string;
    constructor(theName: string) {
        this.name = theName
    }
    static food = "fish"
}
console.log(Octopus.food)

参考文档：https://typescript.bootcss.com/classes.html

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