Create an array inside javascript class to accommodate multiple objects

Question

I am trying to create an array collection of objects inside a JavaScript class.

class Person {
  object = {};
  employees = new Array();

  constructor() {}

  addPerson(name, age) {
    this.object.name = name;
    this.object.age = age;
    this.employees.push(this.object);
  }

  getGroupInfo() {
    return this.employees;
  }
}

let p1 = new Person();
p1.addPerson("Johnny", 40);
p1.addPerson("Mark", 55);
console.log(p1.getGroupInfo());

The output seems to override with the second input that I am providing.

[ 
  { name: 'Mark', age: 55 }, 
  { name: 'Mark', age: 55 } 
]

I am certainly failing to understand the basic javascript way of class creation :-)

Majed Badawi · Accepted Answer · 2021-07-04 19:18:04Z

2

The second call to addPerson is using a reference of the first this.object and changing the values. You can directly add new objects to the employees array as follows:

class Person {
  employees = new Array();
  constructor() {}

  addPerson(name, age) {
    this.employees.push({name, age});
  }

  getGroupInfo() {
    return this.employees;
  }
}

let p1 = new Person();
p1.addPerson("Johnny", 40);
p1.addPerson("Mark", 55);
console.log(p1.getGroupInfo());

answered Jul 4, 2021 at 19:18

Majed Badawi

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Comments

Tushar Shahi · Accepted Answer · 2021-07-04 19:22:32Z

1

p1.addPerson("Johnny", 40);
p1.addPerson("Mark", 55);

Both these statements update and work on the same object : this.object which is a property of the p1 instance. The array becomes something like [x,x].

answered Jul 4, 2021 at 19:22

Tushar Shahi

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Comments

A D · Accepted Answer · 2021-07-04 19:25:42Z

0

this.object inside Person is same for both. So its value getting overridden

class Person {
  name;
  age;

  constructor(name, age) {
    this.name = name;
    this.age = age;
  }
}

employees = new Array();
let p1 = new Person("Johnny", 40);
let p2 = new Person("Mark", 55);
employees.push(p1);
employees.push(p2);
console.log(employees);

answered Jul 4, 2021 at 19:25

A D

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1 Comment

JavaQuest Over a year ago

Thanks! but I wanted to specifically create a collection inside the same object.

JavaQuest · Accepted Answer · 2021-07-04 19:31:57Z

0

I have accepted the first answer which is correct. One other way I could have implemented it :

class Person {
  employees = new Array();

  constructor() {}

  addPerson(name, age) {
    let object = {};
    object.name = name;
    object.age = age;
    this.employees.push(object);
  }

  getGroupInfo() {
    return this.employees;
  }

 }
}

answered Jul 4, 2021 at 19:31

JavaQuest

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