Supporting file for the following article:

wait.js

// This function waits for an unknown amount of time
const wait = (delay, callback) => {
  // setInterval returns an ID. We need this to stop the timer
  const id = setInterval(() => {
    // Generate a random number between 0 and 1
    const rand = Math.random();

    if (rand > 0.95) {
      // Call the callback function. Note the first parameter is an error
      callback(null, 'Congratulations, you have finished waiting.');
      // Stop the timer
      clearInterval(id);
    } else if (rand < 0.01) {
      // Call the callback function. Note we're setting an error now
      callback('Could not wait any longer!', null);
      // Stop the timer
      clearInterval(id);
    } else {
      // Print to STDOUT
      console.log('Waiting ...');
    }
  }, Number(delay));
};