preload-it-example.js

const preload = Preload();

preload.fetch([
  'https://commondatastorage.googleapis.com/gtv-videos-bucket/sample/ForBiggerEscapes.mp4',
  'https://commondatastorage.googleapis.com/gtv-videos-bucket/sample/ForBiggerFun.mp4',
  'https://commondatastorage.googleapis.com/gtv-videos-bucket/sample/ForBiggerJoyrides.mp4'
]).then(result => {
  // use either a promise or 'oncomplete'
});

preload.oncomplete = items => {
  player.src = preload.getItemByUrl('https://commondatastorage.googleapis.com/gtv-videos-bucket/sample/ForBiggerFun.mp4').blobUrl;
  player.play();
}

preload.onprogress = event => {
  document.getElementById('progress').textContent = document.getElementById('progress-bar').style.width = event.progress + '%';
}

preload.onfetched = item => {
  document.getElementById('loaded-items').innerHTML += '<span>' + item.fileName + ' <strong>[' + item.size + ']</strong></span>';
}