終於來到Class的章節了,Class是ES6所新增,在這之前都是使用Prototype去進行物件導向的方式,雖然Class本質上也還是Prototype也就是syntax sugar,但確實使撰寫程式時方便許多

class Person{
    constructor(name, age){
        this.name = name,
        this.age = age
    }
    SayHi(){
        console.log(this.name)
    }
}

class Student extends Person {
    constructor(name, age, grade, email) {
        super(name, age) 
        this.grade = grade;
        this.email = email;
    }
    intro(){
        console.log(`My name is ${this.name} grade is ${this.grade}`)
    }
}

const Nick = new Student("Nick", 22, "9", "text@gmailcom")
console.log(Nick)

可以看到Prototype繼承了Person類別,所以Class還是語法糖並不是像其他OOP語言一樣

Static

顧名思義就是不會改變的,舉圓周率因為不會變,所以把pi設定成Static確保是正確的數值

class Circle{
    static pi = 3.14

    constructor(radius){ 
        this.radius = radius
    }
    areaFN(){
        return this.radius * this.radius * Circle.pi
    }
}

const c = new Circle(10)
console.log(c.areaFN()) //314