newElement = function (spec) {
  var tagName = spec[0];
  var children = spec[1];
  var properties = spec[2];
  var element = document.createElement(tagName);
  for (var i = 0; i < children.length; i++) {
    element.appendChild(newElement(children[i]));
  }
  return element;
}

spec = ['div', [], {}]

document.body.appendChild(newElement())