function Menu() {
  this.opened = false;
  this.openedMenuId = "";
}

Menu.prototype.open = function(id) {
  this.closeOpenMenus();
  document.getElementById(id).style.display = 'block';
  this.openMenuId = id;
  this.opened = true;
}

Menu.prototype.closeOpenMenus = function() {

  if (this.opened) {
    document.getElementById(this.openMenuId).style.display = 'none';
    this.opened = false;
  }
}

myMenu = new Menu();