var searchElement = document.getElementById("search");

searchElement.addEventListener('keyup', function(event) {
  var regex = new RegExp(searchElement.value, "gi");

  var i, downloads = document.getElementsByClassName("download");
  for (i = 0; i < downloads.length; i++) {
    download = downloads[i];
    var id = download.dataset.id;

    if (id.match(regex)) {
      download.style.display = 'block';
    } else {
      download.style.display = 'none';
    }
  }
});