document.addEventListener('DOMContentLoaded', function () {

    'use strict'; // Enforce stricter JavaScript rules.

    // Declare this function's local variables.
    var howdyElement, nameInputElement, nameOutputElement, submitNameButton webappideaElement;

    // Find all needed elements and save them in variables.
    nameInputElement = document.querySelector('#name-input');
    submitNameButton = document.querySelector('#submit-name');
    howdyElement = document.querySelector('#howdy');
    nameOutputElement = document.querySelector('#name-output');
    webappideaElement = document.querySelector('#webappidea');

    // Make things happen when a user clicks on the button element.
    submitNameButton.addEventListener('click', function () {
  var name;

  // Get the string value out of the input textbox.
  name = nameInputElement.value;

  if (name.length === 0) {
     // The user didn't input a name, so use a default.
     nameOutputElement.textContent = 'student';
     howdyElement.classList.remove('enthusiastic');
  } else {
     // The user did input a name, so use it.
     nameOutputElement.textContent = name;
     // Make the paragraph stand out more.
     howdyElement.classList.add('enthusiastic');
       }
    }, false);

 }, false);