// Sleep Method
const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));

// Generic element creation method.
const createEl = (msg) => {
  const newEl = document.createElement('div');
  const elMsg = document.createTextNode(msg);
  newEl.appendChild(elMsg);
  return newEl;
}

// Method using sleep method.
const functionUsingSleep = async () => {
  const el = document.querySelector('#output');
  const firstMsg = createEl('Look, it\'s the first message.');
  const secondMsg = createEl('Look, it\'s the second message.');
  
  el.appendChild(firstMsg);
  
  await sleep(5000); // Wait 5 seconds
  
  el.appendChild(secondMsg);
}

// Init method
functionUsingSleep();