drupal tag filter ajax content

1<?php
2
3/**
4 * @file
5 * Module file for Popolo Custom.
6 */
7
8/**
9 * Implements hook_form_alter().
10 */
11function popolo_custom_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id){
12    
13  // Apply the form_alter to a specific form #id
14  // the form #id can be found through inspecting the markup.
15  if($form['#id'] == 'views-exposed-form-filter-articles-page-1') {
16  
17    // Include js and css, which was defined in libraries.yml.
18    $form['#attached']['library'][] = 'popolo_custom/popolo_custom.enable';	
19    $form['#attached']['library'][] = 'popolo_custom/popolo_custom.forms';
20	
21    // Extract the options from the Views Exposed Filter <select>-list. 
22    $links = $form['field_tags_target_id']['#options'];
23
24    // Iterate over the options ($links) to build an array ($pop_array) of links.
25    $i = 0; // Initiate counter/index
26    $pop_array = array();
27	foreach ($links as $tid => $term_name) {
28		if ($tid == 'All') {
29			$pop_array[$i]['#markup'] = '<span class="filter-tab"><a href="" class="active" id="' . $tid . '">' . $term_name . '</a></span>';
30		}
31		else {
32			$pop_array[$i]['#markup'] = '<span class="filter-tab"><a href="" id="' . $tid . '">' . $term_name . '</a></span>';
33		}
34		$i++; // Increase counter/index
35	} 
36	
37	// Create the item-list the form should render.
38	$form['links'] = [
39	  '#theme' => 'item_list',
40	  '#items' => $pop_array,
41	  '#attributes' => ['class' => ['pop-list']],
42    ]; 
43  } 
44}
45