I'm trying to get a script built. I want to check if a variable exist and include it if it does. Just really struggling to figure out the formatting. Something like
script:
sequence:
target:
entity_id: "{{ entity }}"
{% if variable is defined %}
data: "{{ variable }}"
{% endif %}
This looks like the right answer, since OP's jinja is correct.
OP, you can go to developer tools to test your template syntax against the live data in HA.