menu.js

var modal = {
    modalHolder: document.getElementById('modalHolder'),
    box: document.createElement('div'),
    boxPhoto: document.createElement('img'),
    closeButton: document.createElement('span'),
    openModal: function(source) {
      
      this.modalHolder.appendChild(this.box);
      this.box.appendChild(this.boxPhoto);
      this.box.appendChild(this.closeButton);
      
      this.closeButton.textContent = 'x';
      this.boxPhoto.src = source;
      
      this.box.className = 'modal';
      this.closeButton.className = 'closeButton';
      this.modalHolder.className = 'modalHolder';
      this.boxPhoto.className = 'boxPhoto';
  
      this.closeButton.addEventListener('click', handlers.close);
    },
    closeModal: function() {
      this.modalHolder.innerHTML = '';
      this.modalHolder.className = '';
    }
  }
  
  var handlers = {
    open: function(n) {
      var imageSource = document.getElementsByTagName('img')[n].src;
      modal.openModal(imageSource);
    },
    close: function() {
      modal.closeModal();
    }
  }