Class

终於来到Class的章节了,Class是ES6所新增,在这之前都是使用Prototype去进行物件导向的方式,虽然Class本质上也还是Prototype也就是syntax sugar,但确实使撰写程序时方便许多

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继承了Person类别,所以Class还是语法糖并不是像其他OOP语言一样

Static

顾名思义就是不会改变的,举圆周率因为不会变,所以把pi设定成Static确保是正确的数值

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