Implements basic ```navbar on click addclass``` behavior

basic-nav-bar-behaviour.js

const activateNavbars = (document, window) => {
  let navs = document.querySelectorAll('.nav') || []
  navs.forEach((nav) => {

    let navItems = nav.querySelectorAll('.nav__item')
    if(!navItems.length > 0 ) {
      return
    }
    let selectedItem = null
    
    navItems.forEach((item) => {
      item.addEventListener('click', ()=>{
        item.classList.add('nav__item--selected')
        if(selectedItem){
          selectedItem.classList.remove('nav__item--selected')
        }
        selectedItem = item
      })
      
    })
    /*select first item*/
    navItems[0].click()
    
  })
  
}