Add support for an optional hook to know when cookies were acknowledged.

This fixes https://github.com/infinum/cookies_eu/issues/90

README.md

@@ -101,6 +101,16 @@ If you wish to customize the style of the div the classes are:
 
 If you wish to customize the HTML, create a folder `cookies_eu`, create a partial `_consent_banner.html.erb` and paste the HTML from [here](app/views/cookies_eu/_consent_banner.html.erb)
 
+If you wish to run some arbitrary code when the user acknowledges the cookie message, you can register a callback. This is useful if you wish to persist the user's preference to the database.
+
+```javascript
+document.addEventListener('cookies-eu-acknowledged', function() {
+  // The user has acknowledged cookies! If they're logged in, make an api call
+  // so we remember their preference.
+  fetch('...');
+});
+```
+
 ## Cookies used
 
 This gem uses a cookie called **cookie_eu_consented** to track whether a user has accepted the cookie notice and whether it needs to be shown again or not.

app/assets/javascripts/cookies_eu.js

@@ -29,6 +29,8 @@ var cookiesEu = {
 
     var container = document.querySelector('.js-cookies-eu');
     container.parentNode.removeChild(container);
+
+    document.dispatchEvent(new CustomEvent('cookies-eu-acknowledged'));
   }
 };