what data can I get when overriding a change_form

hey, I want to add some more functionality to the admin in the change_form
so I created a file templates\admin\product\change_form.html:

{% extends "admin/change_form.html" %}
{% load i18n admin_urls %}
{% block field_sets %}
    {% for fieldset in adminform %}
        {% include "admin/includes/fieldset.html" %}
    {% endfor %}
    <h1> hey </h1>
    {{ request }}
{% endblock %}

and I do see I something added to the HTML and I can’t access it from the javascript:

my question is:
what information can I get from what Django already retrieve, like the name of the product and so on?
what is the recommended way to implement my own js file in the admin change_form?
and why I can not access request from my javascript?
Thank you!

Keep in mind that the templates are rendered to plain HTML in Django before being sent to the browser. This means that there are no variables accessible from JavaScript (which is running in the browser). You would have to add code to your template (perhaps using the json_script tag) to expose specific values.