Setting foundation 6 data-accordion-menu dynamically with javascript

Question

I am trying to dynamically build an array within Foundation 6's accordion menu by using pure javascript. I cannot seem to figure out how to inject data-accordion-menu into the div. The original code looks like this:

    <div class="button_moreinfo row">
      <ul class="vertical menu" data-accordion-menu>
        <li>
          <a href="#">Saturday, 3/19 @ 6:05PM</a>
          <ul class="menu vertical nested">
            <li><a href="#">Person A has 25pts</a></li>
            <li><a href="#">Person B has 5pts</a></li>
            <li><a href="#">Person C has been pulled from the game for a sprained ankle</a></li>
          </ul>
        </li>
      </ul>
    </div>

I am trying to rebuild it dynamically with this:

    newElementAC2.id=vertical_menu[0];newElementAC2.className ="vertical menu";
   newElementAC2.setAttribute('data',"data-accordion-menu");
   newElementAC1.appendChild(newElementAC2);