phpjs/experimental/info/extension_loaded.js

php.js offers community built php functions in javascript

function extension_loaded(name) {
  // http://kevin.vanzonneveld.net
  // +   original by: Brett Zamir (http://brett-zamir.me)
  // *     example 1: extension_loaded('strings');
  // *     returns 1: true

  return !!(this.php_js && this.php_js.ini && this.php_js.ini['phpjs.loaded_extensions'] && // dl() also ensures indexOf is added for IE
      this.php_js.ini['phpjs.loaded_extensions'].local_value.indexOf(name) !== -1);
}