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 #}