setstock_webforms.module

<?php
/**
 *  @file
 *  CNCEx Webform Submissions
 */


use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Cache\Cache;
use Drupal\node\Entity\Node;
use Symfony\Component\HttpFoundation\Request;
use Drupal\Core\Url;

function setstock_webforms_form_alter(&$form, FormStateInterface $form_state, $form_id) {


  // REQUEST A QUOTE
  // SETS PRODUCT TITLE
  if(isset($form['#webform_id']) &&
     $form['#webform_id'] == 'request_a_quote') {

      // GET PATH OF NODE THAT LOADED THE FORM
      $request = \Drupal::request();
      $referer = $request->headers->get('referer');

      $base_url = Request::createFromGlobals()->getSchemeAndHttpHost();

      // Getting the alias or the relative path.
      $alias = substr($referer, strlen($base_url));

      // Getting the node.
      $params = Url::fromUri("internal:" . $alias)->getRouteParameters();
      $entity_type = key($params);
      $node = \Drupal::entityTypeManager()->getStorage($entity_type)->load($params[$entity_type]);

      // EXTRACT VALUE OF FIELD
      if (isset($node) && is_object($node)) {
        $form['elements']['product_title']['#default_value'] = $node->get('title')->value;
      }


  }
}