/**
 * Wrapper around a HTML element holding messages.
 *
 * @param id
 *   The DOM ID of the element.
 *
 * @constructor
 */
function MessageElement(id) {
  "use strict";

  /**
   * Private reference to the DOM element holding messages.
   *
   * @type {HTMLElement}
   */
  var element;

  /**
   * Private initializer.
   *
   * @param id
   */
  function init(id) {
    element = document.getElementById(id);
    if (!element) {
      throw new Error("Element id " + id + " not found in the DOM.");
    }
  }

  this.set = function (message) {
    element.innerHTML = message;
  };

  init(id);
}