vars_to_javascript.module

<?php

/**
 * @file
 * Contains vars_to_javascript.module.
 */

use Drupal\Core\Routing\RouteMatchInterface;

/**
 * Implements hook_help().
 */
function vars_to_javascript_help($route_name, RouteMatchInterface $route_match) {
  switch ($route_name) {
    // Main module help for the vars_to_javascript module.
    case 'help.page.vars_to_javascript':
      $output = '';
      $output .= '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('Transform PHP types to JavaScript') . '</p>';
      return $output;

    default:
  }
}

function phpexcel_preprocess_html(&$variables) {
  $set_bottom_script = [
  '#type' => 'inline_template',
  '#template' => '{{ javascript|raw }}',
  '#context' => [
  'javascript' => set_bottom_script(),
  ]      
  ];

  $variables['page_bottom'] = ['bottom_script' => $set_bottom_script];
}

function set_bottom_script($js = NULL){
  global $bottom_script ;
  if ($js) {
    $bottom_script = $js;
  }else{
    return $bottom_script;
  }
}