Clerk.js allows you to write custom javascript functions, that adds new functionality to the Designs.

Formatters should be inserted as a configuration for Clerk.js, in the tracking-script that is inserted on all pages.

For Prestashop this file contains the tracking-script:


An example can be seen below. Please be aware this is Clerk V2 (latest version):

<!-- Start of E-commerce Personalisation tool - -->
<script type="text/javascript">
var e=d.createElement('script');e.type='text/javascript';e.async=true;
var s=d.getElementsByTagName('script')[0];s.parentNode.insertBefore(e,s);
w.__clerk_q=w.__clerk_q||[];w.Clerk=w.Clerk|| function(){ w.__clerk_q.push(arguments) };
Clerk('config', {
key: '{$clerk_public_key}',
collect_email: {$clerk_datasync_collect_emails},
language: '{$language}',
formatters: {
log_price: function(price) {
<!-- End of E-commerce Personalisation tool - -->

You can write any number of Formatters, separated by comma:

formatters: {
   log_price: function(price) {
   calculate_discount: function(price,special_price) {
      return price-special_price;
   substring: function(text) {
      var short_string = text.substring(0,20);
      return short_string;

After creating your Formatters, you can use them in your Designs using this syntax:

{{ price | log_price }} {{ price | calculate_discount |  special_price }}

This effectively allows you to create any functionality in your Designs that you require.

Did this answer your question?