typescript-类和接口

TypeScript 具备面向对象编辑的基础语法，包括interface,class ,enum等；也具备封装，基础，多态等面向对象的基本特征

//定义矩形类
class Rectangle {
    //成员变量
    private width: number
    private length:number
    //构造函数
    constructor(width:number,length:number){
        this.width = width;
        this.length = length;
    }
    //成员方法
    public area(): number{
        return this.width * this.length
    }
}
    //定义正方形
class Square extends Rectangle{
    constructor(side:number){
        //调用父类构造
        super(side,side)
   }
}
let s = new Square(10)
console.log('正方形面积为:'+s.area())

//类、接口、枚举
//定义枚举
enum Msg{
HI = 'Hi',
HELLO = 'Hello'
}
//定义接口，抽象方法接收枚举参数
interface A{
    say(msg: Msg):void
}
//实现接口
class B implements A{
    say(msg: Msg):void {
        console.log(msg +'I am B')
    }
}
//初始化对象
let a:A = new B()
// 调用方法，传递枚举参数
a.say(Msg.HI)