base-page.js

function BasePage() {}

BasePage.create = function(pageConstructor) {
    return new pageConstructor();
}

module.exports = BasePage;

index.1.js

const dog = require('./page.1');

console.log(dog.name);

index.js

const dog = require('./page');

console.log(dog.name);

page.1.js

const BasePage = require('./base-page');

function Page() {
    this.name = getName();
}

module.exports = BasePage.create(Page);

const getName = () => 'Index';

page.js

const BasePage = require('./base-page');

function Page() {
    this.name = getName();
}

module.exports = BasePage.create(Page);

function getName() {
    return 'Index';
}