类
访问修饰符
| 类型 | 作用 | 特点 |
|---|---|---|
| public | 公共的 | 可以随意调用 |
| private | 私有的 | 只有自身可以调用 |
| protected | 受保护的 | 只有自身和子类可以调用 |
| readonly | 只读 | 只能读取不能修改 |
| static | 静态的 | 只能从构造函数上获取 |
访问修饰符的使用类似于大多数强类型语言
ts
class User {
public name: string
private age: number
constructor(name: string, age: number) {
this.name = name
this.age = age
}
}
const user = new User("张三", 18)
// 这里name属性时公共的，可以直接获取
user.name
// 由于age是私有属性只能内部获取
user.age // 报错继承
ts
class Person {
protected name: string
protected age: number
constructor(name: string, age: number) {
this.name = name
this.age = age
}
}
class User {
constructor(name: string, age: number) {
super(name, age)
}
public sayHello(): string {
return `hello,My name is ${this.name},I am ${this.age}`
}
}
const user = new User("张三", 18)
// name 和 age 是 protected 只能是子类获取
user.name //报错
user.age //报错抽象类
和大多数强类型语言一样，ts 有抽象类这个概念，抽象类类似于接口，不能实例化，使用 abstract 关键字
ts
abstract class Person {
public name: string
protected age: number
public abstract sayHello(): string
constructor(name: string, age: number) {
this.name = name
this.age = age
}
}
class User extends Person {
constructor(name: string, age: number) {
super(name, age)
}
public sayHello(): string {
return `hello,My name is ${this.name},I am ${this.age}`
}
}
const user = new User("张三", 18)小技巧
优化代码，下面两种方式是等同的
ts
// befor
class User {
public name: string
public age: number
constructor(name: string, age: number) {
this.name = name
this.age = age
}
}
// after
class User {
constructor(public name: string, public age: number) {}
}