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

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

An example can be seen below:

<!-- Start of E-commerce Personalisation tool - -->
<script type="text/javascript">
  window.clerkAsyncInit = function() {
          key: 'O7UITkJIXqXibeQF9ONobiGGKYYKtbvh',
          templateFormatters: {
             log_price: function(price) {

      var e = document.createElement('script'); e.type='text/javascript'; e.async = true;
      e.src = document.location.protocol + '//';
      var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(e, s);
<!-- End of E-commerce Personalisation tool - -->

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

templateFormatters: {
   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 TemplateFormatters, you can use them in your Designs using this syntax:

{{ substring name }} {{ calculate_discount price special_price }}

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

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