//myscript.js

/**
 * (un)packing menu items
 * @param string - id of menu items block
 * @return void
 */
function packIt(myId) {

  var myEl = document.getElementById(myId);
  
  if (myEl.style.display == "block")
    myEl.style.display = "none";
  else
    myEl.style.display = "block";
}