telecom.js

const mainNav = document.querySelector('.main-nav');
const menu = document.querySelector('#menu');

toggleMenu = () => {
  mainNav.classList.toggle('isDisplayed');
  if (menu.getAttribute('src') === './images/menu.svg') {
    menu.setAttribute('src', './images/menu-purple.svg');
  } else {
    menu.setAttribute('src', './images/menu.svg');
  }
};

menu.addEventListener('click', toggleMenu);