class Cat implements Animal {//报错了,没有实现进食的功能} 4. 只读关键字(readonly) 用来定义只读的字段,使得字段只能在创建的时候赋值一次。 class Human { name: string; readonly id: number; constructor(name: string, id: number) {this.name =name;this.id =id; } } let human=newHuman('陈皮...
private name: string constructor(name: string) { = name } } let demo = new User("张三") console.log(demo.name) //报错 name为私有属性 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 2. protected class User { protected name: string constructor(name: string) { = name } } class...
但是 TypeScript 并不会阻止你与其它字符串比较,语言不会把那些表达式识别为类型保护。 4.3 instanceof 关键字 interface Padder { getPaddingString(): string; } class SpaceRepeatingPadder implements Padder { constructor(private numSpaces: number) {} getPaddingString() { return Array(this.numSpaces + 1)...
classDog{constructor(name:string){this.name=name}publicname:string// 类型注解// 私有成员privateeat(){console.log(`dog is eating`)}run(){console.log(`${this.name}is running`)}} 如果private修饰constructor,表示这个类既不能被实例化,也不能被继承。 5.2.3 protected Protected修饰需要保护的成员—...
private width: number private height: number constructor(width: number, height: number) { super() // 【即使父类没有属性,也要调用super。】 this.width = width this.height = height } getArea() { return this.width * this.height } } class Circle extends Shape { private r: number constructor...
private看起来挺安全了,但足够安全吗?未必,毕竟它还是能够在类的内部被改变的,想要更安全,我们需要下一个”工具“。 readonly(只读) 实例创建后无法更改 readonly并不是修饰符,虽然看起来像,它能和修饰符一起配合使用。 class Calculator{ protected readonly precision:number = 2; ...
如果使用private来修饰属性, 那么表示这个属性是私有的 可以在类的内部使用 错误示例: image-20211128161154773 正确示例: 代码语言:typescript AI代码解释 classPerson{name:string;age:number;privategender:string;constructor(name:string,age:number,gender:string){this.name=name;this.age=age;this.gender=gender;}...
private age: number; protected gender: string; constructor(name: string, age: number, gender: string) { this.name = name; this.age = age; this.gender = gender; } sayHello(): void { console.log(`hello, my name is ${this.name}, I'm ${this.age} years old`); ...
protected修饰符与private修饰符的行为很相似,但有一点不同,protected成员在派生类(子类)中仍然可以访问 class Animal {protected name: string;public constructor(theName: string) {this.name = theName}}class Cat extends Animal{constructor(theName:string){super(theName)}public move(distanceInMeters: number...
@Controller() export class AppController { // 2. 如果他是这么写的我可以理解 // private readonly appService: AppService constructor(private readonly appService: AppService) {} @Get('/hello') getHello(): string { // 1. 为什么在这里可以通过this访问appService return this.appService.getHello...