JavaScript - Mostrar varias ventanas modales

'use strict';

 /**

  * modalWindow

  * @param {HTMLElement} modal 

  * @param {HTMLElement} btnOpen 

  * @param {HTMLElement} btnClose 

  */

 function modalWindow(modal, btnOpen, btnClose) {

     btnClose.addEventListener('click', (e) => {

         e.preventDefault();

         modal.classList.remove('open');

     });

     btnOpen.addEventListener('click', (e) => {

         e.preventDefault();

         modal.classList.add('open');

     });

 }

 window.onload = function() {

     let modal = document.getElementById('modal');

     let btnClose = modal.querySelector('.close');

     let btnOpen = document.getElementById('btn');

     modalWindow(modal, btnOpen, btnClose);

 };