Call class directly and not via instance variable

Question

I have created the following two classes in my classes.js:

class Person {
    constructor(firstName, lastName) {
        this.firstName = firstName;
        this.lastName = lastName;
    }

    display() {
        console.log(this.firstName + " " + this.lastName);
    }
}

module.exports = {
    Person
};

As you can see I am exporting the two classes via module.exports.

Person = require('./classes.js');

const someone1 = new Person("First name", "Last name"); // <-- does NOT work

const someone = new Person.Person("First name", "Last name"); // does work
someone.display();

However, when calling the classes I get an error, when calling the class directly.

Any suggestions how to call the class directly?

I appreciate your replies!

module.exports = Person; If you have two classes, well, you want either different files or to do something like Person = require('../classes.js').Person; — Liam MacDonald
– Liam MacDonald, Commented Apr 15, 2019 at 9:30
Hint: You're exporting an object { Person: Person } from the file. — 31piy
– 31piy, Commented Apr 15, 2019 at 9:34

alizahid · Accepted Answer · 2019-04-15 09:39:34Z

3

If you want all your classes in one file called classes.js, then this should work;

// classes.js

class Person {
  // ...
}

class Vehicle {
  // ...
}

module.exports = {
  Person,
  Vehicle
}

// some-other-file.js

const { Person } = require('../classes')

const person = new Person('First', 'Last')

Although to keep things easy to understand, my recommendation would be to split your class into multiple files and then export each class from its file directly;

class Person {
  // ...
}

module.exports = Person

const Person = require('../classes/person')

// do something

answered Apr 15, 2019 at 9:39

alizahid

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Comments

1565986223 · Accepted Answer · 2019-04-15 09:53:11Z

1

In this case you're exporting an object containing Person class

module.exports = {
    Person
};

So when you import like Person = require('./classes.js')

You're actually importing the exported object. So Person after you've imported is similar to

Person = {
  Person
};

You can either change the export by assigning the desired export object to module.exports like:

module.exports = Person

or change your import to use destructuring assignment to import like (notice the curly braces):

const { Person } = require('./classes.js');

answered Apr 15, 2019 at 9:53

1565986223

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Comments

mbojko · Accepted Answer · 2019-04-15 09:32:04Z

1

If

module.exports = {
    Person
};

therefore

Person = require('./classes.js').Person;

Alternatively, you can

module.exports = Person;

and

Person = require('./classes.js');

answered Apr 15, 2019 at 9:32

mbojko

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Comments

Iurii Tkachenko · Accepted Answer · 2019-04-15 09:46:38Z

1

In classes.js you are exporting Person as an object property. So to make it work as you expect you can either do Destructuring Assignment

const { Person } = require('./classes')

Or just require class directly from classes.js file.

const Person = require('./classes').Person

Alternatively, and it's a better option, in my opinion, you can separate Person to its own file and export it by default.

File ./Person.js

class Person {
    constructor(firstName, lastName) {
        this.firstName = firstName;
        this.lastName = lastName;
    }

    display() {
        console.log(this.firstName + " " + this.lastName);
    }
}

module.exports = Person

And then in your main file just do:

const Person = require('./Person');

edited Apr 15, 2019 at 9:46

answered Apr 15, 2019 at 9:38

Iurii Tkachenko

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