Example of a pager (pagination) on php:

function showpager($currentIndex = 0, $buttons = 5, $totalPages = 50) {
  $currentPage = $lowerLimit = $upperLimit = min($currentIndex, $totalPages);
  //Search boundaries


Note : On drupal the best practice is use drupal behaviors but not JS or Jquery codes such as:
<button onclick='myFunction()'>Click</button>

keyvalue.expirable service allow to save Key / Value variable in the database.

Example:

// Save without date limit.
\Drupal::service('keyvalue.expirable')->get('my_module')->set('my_var', 123);

Webmin and Virtualmin Change IP access control from shell terminal.

Edit file: /etc/webmin/miniserv.conf
vim /etc/webmin/miniserv.conf

Change:
allow=OLD_IP to New IP
Example:
allow=123.214.123.123 85.25.65.45 45.65.85.36

Drush allow to download and install drupal core, drupal modules and drupal themes.
Note : It is recommended to use composer to manage drupal 8, modules and themes.