Clerk.js's template language is a subset of the Liquid template language.

Here is a simple example of a template:

<h1>{{ headline }}</h1>
  
<ul class="product-list">
  {% for product in products %}
    <li class="product">
      <h2 class="product-name">{{ product.name }}</h2>
 
      <img src="{{ product.image }}" title="{{ product.name }}" />
 
      {% if product.price < product.list_price %}
        <div class="list-price">${{ product.list_price | money }}</div>
        <div class="price">${{ product.price | money }}</div>
        <div class="discount">You Save: {{ product.price / product.list_price * 100 | round }}%</div>
      {% else %}
        <div class="price">${{ product.price | money }}</div>
      {% endif %}
        
      <a href="{{ product.url }}">Buy Now</a>
    </li>
  {% endfor %}
</ul>

Inserting Values

Everything within {{ and }} is processed by the template engine as a variable to be inserted into the page eg. {{ headline }}.

If a variable contains a deeper structure, like a dictionary, it can be accessed by dot syntax like so
{{ product.price }}.

A value can also be a expression such as {{ 100 - product.price / product.list_price * 100}}.

<h1>{{ headline }}</h1>

<div class="price">{{ product.price }}</div>

<div class="list-price">{{ 100 - product.price / product.list_price * 100}}</div>

If-else statements

Flow control if supported via if-else statements denoted by curly braces and percent signs: {% and %}.

If-statements can be used to check simple booleans, numerical values and strings.

Some examples:

{% if product.on_sale %}
  On Sale
{% endif %}

{% if product.stock_count < 10 %}
  Only few in stock!
{% else %}
  Lots in stock.
{% endif %}

{% if product.vendor == "Awesome Shoes" %}
  These shoes are awesome!
{% endif %}

{% if product.title contains 'Pack' %}
  This product's title contains the word Pack.
{% endif %}

Statements can also be combined for more advanced logics:

{% if product.type == "Shirt" or product.type == "Shoes" %}
  This is a shirt or a pair of shoes.
{% endif %}

The available operators in Liquid are these:

For-loops

Iterating over an array of values is done as follows:

{% for product in products %}
  {{ product.name }}
{% endfor %}

To make looping over a loop easier each loop has an associated loop object only available within the loop body with the following fields:

Here is an example of using the loop object to write a comma-separated list of sizes for each product.

{% for size in product.sizes %}
 {{ size }}{% if not loop.last %}, {% endif %}
{% endfor %}

Small, Medium, Large, X-Large

Assigning Variables

You can assign variables in the template language assign keyword like this {% assign myvar = 123 + 456 %}.

Assigned variables will be available in the current scope (and all sub.-scopes) after the assign statement.

{% for product in products %}
  {% assign is_on_sale = product.price < product.list_price %}
  <h1>{{ product.name }}</h1>
  {% if is_on_sale %}
    <div class="on-sale-badge">On Sale</div>
  {% endif %}
{% endfor %}

Comments

Besides HTML comments (which will be inserted into the generated HTML) you can also use comments build into the template language that will only be visible in the template.

Comments are started with {% comment %} and ended with {% endcomment %}.

Formatters

Formatters can be used to format values before they are inserted into the page. Formatters are applied to a value by using |.

{{ product.price | money }}

Formatters can even be used with several arguments, if needed:

{{ product.price | cost product.list_price }}

Multiple formatters can be used by being chained after each other. They will be applied in the order they are listed reading from left to right.

{{ product.price | round | money }}

Clerk.js comes with these built-in formatters:

You can add you own formatter functions in the Clerk.js Configuration.
A formatter function takes one or more arguments and returns a string or number. Here is an example of our round formatter:

Clerk('config', {
  formatters: {
    round: function(x) {
      return Math.round(x).toString();
    },
    cost: function(price, price2) {
      if (price > price2) {
        return "This is a premium product on sale";
      }
      else {
        return "This is is a regular product";
      }
    }
});

Content Variables

When rendering the main template of a Content the following variables are always available:

To simplify the template language all the sub-keys of response, content, formatters and globals are merged into the root scope such that {{ globals.is_mobile }} can be accessed directly as {{ is_mobile }} or {{ response.count | formatters.round }} can be access directly as {{ count | round }}.

Thus response, content, formatters and globals can be considered namespaces that are only explicitly needed in terms of a name clash.

Global Variables

Any template will always have the globals configured under Configuration available as the value globals.

UI Component Variables

Each UI Component may add more variables to the root scope. If so this will be documented under the specific UI component.