// Get a reference to an element through an id

const numberElement = document.getElementById('demo');

​

// Define a function to generate random numbers

function getRandomNumber() {

  return Math.floor(Math.random() * 100);

}

​

// Update the specified id element with a new random number every second

const intervalId = setInterval(() => {

  const randomNumber = getRandomNumber();

  numberElement.textContent = randomNumber;

}, 1000);

​

// Stop the interval after 20 seconds

setTimeout(() => {

  clearInterval(intervalId);

}, 20000);

​