Include es6 class from external file in Node.js

export class MyClass
{
   constructor(arg){
    this.arg = arg;
}
}

import {MyClass} From'./MyClass.js'

class OtherClass{
 arg_two;

}

import {OtherClass} From'./OtherClass.js'

class1 = new OtherClass();
class1.arg_two.arg = 'class';

console.log(class1.arg_two.arg);

Either do

module.exports = class MyClass {
    constructor(arg){
        console.log(arg);
    }
};

and import with

var a = require("./class.js");
new a("fooBar");

or use the newish syntax (may require you to babelify your code first)

export class MyClass {
    constructor(arg){
        console.log(arg);
    }
};

and import with

import {myClass} from "./class.js";

export default class myClass {
   constructor(arg){
      console.log(arg);
   }
}

Other file:

import myClass from './myFile';