Builtin hostname feature in JS

hostname.js

$(document).ready(function() {
  $linkField = $('[name="form-link"]');
  $sourceField = $('[name="form-source"]');
  $linkField.keypress(function() {
    $tempA = document.createElement('a');
    $tempA.href = $linkField.val();
    $sourceField.val($tempA.hostname);
    $tempA.remove();
  });
});