var form = document.getElementById("form");
var newUl = document.createElement('ul');
var newLi = document.createElement('li');

newButton.addEventListener("click", function(){
form.appendChild(newUl);
newUl.id = "formList";
var formList = document.getElementById("formList");
formList.appendChild(newLi);
formList.appendChild(newLi);
formList.appendChild(newLi);
}

//// html
<div id="form">

 </div>

var form = document.getElementById("form");

function newLi() {
    return document.createElement("li");
    }

newButton.addEventListener("click", function(){
    //Create a separate <ul> each time, give it a class, and add it.
    var newUl = document.createElement("ul");
    newUl.class = "formList";
    form.appendChild(newUl);

    //create new <li>'s and append them
    formList.appendChild(newLi());
    formList.appendChild(newLi());
    formList.appendChild(newLi());

    //smile. :D
    }

var form = document.getElementById("form");
var newUl = document.createElement('ul');

newUl.id = "formList";
form.appendChild(newUl);

newButton.addEventListener("click", function(){
    var newLi = document.createElement('li');
    newUl.appendChild(newLi);
})

function addNode(){
  var x = document.createElement("ul");
  x.setAttribute("id","myList");
  document.body.appendChild(x);

  var myListItem = document.createElement("li");
  var textNode = document.createTextNode("List Item one");
  var t2 = document.createTextNode("second item");

  myListItem.appendChild(textNode);

  document.getElementById("myList").appendChild(newLi("FirstItem"));
  document.getElementById("myList").appendChild(newLi("Second Item"));
  document.getElementById("myList").appendChild(newLi("Third Item"));
  document.getElementById("myList").appendChild(newLi("Fourth Item"));
}