Use require/new to instantiate a new object in node.js

Question

I have very simple beginner problem using node.js but I cannot seem to get it to work correctly.

All I want is to be able to create objects using the 'new' operator in the index.js file. For demonstration purposes, I have created a simple Person object inside a Person.js file (which lies in the same directory as my index.js) like this:

class Person {
  constructor() {
    this._name = 'bob';
  }

  set name(name) {
    this._name = name
  }

  get name() {
    return this._name;
  }  
}

Now I want to do something like this (in the index.js file):

var p = require('./Person.js')
var bob = new p.Person()

The error message I get is telling me that Person is not a constructor:

var bob = new p.Person()
      ^

TypeError: p.Person is not a constructor
at Object.<anonymous> (/home/.../index.js:59:11)
at Module._compile (module.js:652:30)
at Object.Module._extensions..js (module.js:663:10)
at Module.load (module.js:565:32)
at tryModuleLoad (module.js:505:12)
at Function.Module._load (module.js:497:3)
at Function.Module.runMain (module.js:693:10)
at startup (bootstrap_node.js:188:16)
at bootstrap_node.js:609:3

Any help is greatly appreciated.

Answer 1

If you want to require or import class/function/object/anything from another JS file, you need to export that and import/require that in your current file. These are called modules.

In your case, You need to export the Person class after creating. Otherwise JS doesn't have any reference to it. Add

module.exports = Person

below the Person class. Now you can instantiate by

const Person = require('./person');
const p = new Person();

For the new ES6 classes you can use import/export as well.

// Export Person Class

export default class Person {
    ....
}

// Now, import
import Person from './person'