Near complete rewrite of EU Cookie Compliance JS for reliability:

- Now detaches and re-attaches without issues.

- Correctly hides the overlay if open when detached so that scroll
  blocking and ally.maintain.disabled are disengaged.

- Reworked into JavaScript classes and event subscribers.

- Focus locking now works more reliably in most cases; still shows when
  the pop-up is auto shown by the module's JavaScript, but that can be
  fixed later with a rework of focus hiding.

See: neurocracy/omnipedia#46

javascript/eu_cookie_compliance.decide_later.js

@@ -1,5 +1,5 @@
 // -----------------------------------------------------------------------------
-// Omnipedia - Site theme - EU cookie compliance decide later button
+// Omnipedia - Site theme - EU Cookie Compliance decide later button component
 // -----------------------------------------------------------------------------
 
 // This adds an event handler to close the pop-up when clicking the "Decide
@@ -9,12 +9,12 @@ AmbientImpact.onGlobals([
  'Drupal.eu_cookie_compliance',
 ], function() {
 AmbientImpact.on([
- 'OmnipediaSiteThemeEuCookieComplianceElements',
-], function(euCookieComplianceElements) {
+ 'OmnipediaSiteThemeEuCookieCompliance',
+], function(euCookieCompliance) {
 AmbientImpact.addComponent(
  'OmnipediaSiteThemeEuCookieComplianceDecideLater',
 function(
- euCookieComplianceDecideLater, $
+ euCookieComplianceDecideLater, $,
 ) {
 
  'use strict';
@@ -36,44 +36,35 @@ function(
  this.addBehaviour(
  'OmnipediaSiteThemeEuCookieComplianceDecideLater',
  'omnipedia-site-theme-eu-cookie-compliance-decide-later',
- euCookieComplianceElements.getBehaviourSelector(),
+ '#sliding-popup',
  function(context, settings) {
 
- /**
- * The cookie compliance pop-up, if any, wrapped in a jQuery collection.
- *
- * @type {jQuery}
- */
- let $popUp = euCookieComplianceElements.getPopUp();
+ $(this).on(
+ `PrivacyPopupConstructed.${eventNamespace}`,
+ function(event, popup) {
 
- // Bail if we can't find the pop-up.
- if ($popUp.length === 0) {
- return;
- }
+  popup.$popup.find(`.${decideLaterButtonClass}`).on(
+  `click.${eventNamespace}`,
+  Drupal.eu_cookie_compliance.toggleWithdrawBanner,
+  );
 
- // Event handler to close the pop-up when the "Decide later" button is
- // clicked.
- $popUp.find('.' + decideLaterButtonClass).on(
- 'click.' + eventNamespace,
- Drupal.eu_cookie_compliance.toggleWithdrawBanner
- );
+ // Attach binds a one-off handler to the PrivacyPopupDestroyed event which
+ // removes the click event handler.
+ }).one(`PrivacyPopupDestroyed.${eventNamespace}`, function(event, popup) {
 
- },
- function(context, settings, trigger) {
+ popup.$popup.find(`.${decideLaterButtonClass}`).off(
+ `click.${eventNamespace}`,
+ Drupal.eu_cookie_compliance.toggleWithdrawBanner,
+ );
 
- /**
- * The cookie compliance pop-up, if any, wrapped in a jQuery collection.
- *
- * @type {jQuery}
- */
- let $popUp = euCookieComplianceElements.getPopUp();
+ });
 
- // Bail if we can't find the pop-up.
- if ($popUp.length === 0) {
- return;
- }
+ },
+ function(context, settings, trigger) {
 
- $popUp.find('.' + decideLaterButtonClass).off('click.' + eventNamespace);
+ // Remove just the constructed event as the destroyed event needs to run
+ // and will be invoked and then removed as it's a one-off event.
+ $(this).off(`PrivacyPopupConstructed.${eventNamespace}`);
 
  }
  );