Using the sample code below, you can display custom html, javascript, etc. based on any criteria. For example, set parameter as false if specific product category is found:

{% if context == 'receipt' %}

    {% set candy = true %}

    {% for item in items %}
        {% if item.category == 'WHOLESALE' %}
            {% set categoryFound = false %}
        {% endif %}
    {% endfor %}

    {% if categoryFound %}
<h1>Success!</h1>
    {% endif %}

{% endif %}{# context == receipt #}