Javascript，添加构造函数的类

Question

我有点新的js + ES6 +类;我有在构造函数内部创建函数的问题。

#1. I need to add new Hobby, a person allowed to have plenty hobbies ; 
#2. I don't know how to show all the data of students; 

另一个问题是在comments，在情况下，如果你想回答这个问题也是如此，如果没有我也很好。 所以这里是我的代码：

class Student { 
    constructor(name,hobbies){ 

    this.name = name; 

    var hobby = new Set(); //do I set here or inside the function ?? 
//since the function addHobbies also need, then it's fine to be global right ? 


    this.hobbies = (hobbies) => { //function ES6 like this right ?? 

     this.hobbies = hobby.add(hobbies); 

     return this.hobbies; //can I return hobby instead of this.hobbies ?? 
    }; 
    } 
    setName(newName){ 
    this.name = newName; 
    } 

    addHobbies(newHobbies){ 
    this.Hobbies = hobby.add(newHobbies); //it should be like this to add >> to set ? 
    } 


    getName(){ 
    return this.name; 
    } 

    getHobbies(){ 
    return this.hobbies; 
    } 
} 

以及如何返回所有的数据吗？

let andy = new Student("andy","dance"); 
let vince = new Student("vince","codding"); 

所以它会显示所有的学生 - 由getCode()属性？

Answer 1

试试这个：

class Student { 
    constructor(name, hobbies) { 
    this.name = name; 

    // Allow passing both an array of hobbies and a single hobby 
    this.hobbies = Array.isArray(hobbies) ? new Set(hobbies) : new Set([hobbies]); 
    } 

    setName(newName) { 
    this.name = newName; 
    } 

    addHobbies(newHobbies) { 
     if (Array.isArray(newHobbies)) { 
      newHobbies.forEach((hobby) => this.hobbies.add(hobby)); 
     } else { 
      this.hobbies.add(newHobbies); 
     } 
    } 

    getName() { 
    return this.name; 
    } 

    getHobbies() { 
    return this.hobbies; 
    } 
} 

let andy = new Student("andy","dancing"); 
let vince = new Student("vince",["codding", "running"]); 
andy.addHobbies("slipping"); 
vince.addHobbies(["running", "eating"]); 

Answer 2

我在这里设置或里面的功能？

这取决于你需要什么。你是否想让每个Student代替一组业余爱好，还是每次调用该函数时都想创建一个新集？

this.hobbies = (hobbies) => { //function ES6 like this right ?? 
    this.hobbies = hobby.add(hobbies); 

这并不在所有的工作。您正在使用函数值创建属性，但是当调用该方法时，您将覆盖属性，返回值为add method。

---

要使其工作，我建议你做的.hobbies设置instance property instead of a local variable。

class Student { 
    constructor(name, ...hobbies) { 
    this.name = name; 
    this.hobbies = new Set(); 
    this.addHobbies(...hobbies); 
    } 

    getName() { 
    return this.name; 
    } 
    setName(newName) { 
    this.name = newName; 
    } 

    getHobbies() { 
    return this.hobbies; 
    } 
    addHobbies(...newHobbies) { 
    for (const newHobby of newHobbies) 
     this.hobbies.add(newHobby); 
    } 
} 

或者，如果你坚持使用本地构造变量，它应该是这样的：

class Student { 
    constructor(name, ...hobbies) { 
    this.name = name; 
    this.hobbies = new Set(...hobbies); 

    this.getHobbies =() => { 
     return this.hobbies; 
    }; 
    this.addHobbies = (...newHobbies) => { 
     for (const newHobby of newHobbies) 
     this.hobbies.add(newHobby); 
    }; 
    } 

    … // further methods (for name etc) 
} 

Answer 3

你是在正确的方向。我已经重写了你的班级，去做我认为更接近你想要达到的目标的班级。

播放与代码：https://jsbin.com/vejumo/edit?js,console

而这里的重写类：

class Student { 
    constructor(name, hobbies = []){ 

    this.name = name; 

    // new Set() is used to work with objects. It does not work with well with strings 
    // Let's use an array to store the hobbies. 
    // if a hobby or an hobbies array is passed, store it, otherwise set an empty array. 
    this.hobbies = this.parseHobbies(hobbies); 
    } 

    // This function will normalize the hobbies to an Array 
    parseHobbies(hobbies) { 
    if (typeof hobbies === "string") { 
     // hobbies is a string, means it's a single hobby and not an array 
     return [hobbies]; 
    } 
    // Assuming the hobbies is a an Array 
    return hobbies; 
    } 

    setName(newName) { 
    this.name = newName; 
    } 

    // this function will allow you to add a single hobby to the array 
    addHobbies(hobbies = []) { 
    // Same logic like in constract, this can accept a string or an array 
    // We use Array.concat and push to append to array 
    this.hobbies = this.hobbies.concat(this.parseHobbies(hobbies)); 
    } 

    getName() { 
    return this.name; 
    } 

    getHobbies() { 
    return this.hobbies 
    } 

    // This will return all student attributes. 
    getAttributes() { 
    // Return a copy of all the attributes instead of returning references 
    return Object.assign({}, this); 
    } 
} 

let george = new Student("George", "Sports"); 
george.addHobbies(["Singing", "Fishing"]); 
george.addHobbies("Dancing"); 
console.log(george.getAttributes());