Fix jQuery preference order to prevent conflicts with third-party widgets

[marcelo-maldonado95]

Problem

When using django-select2 with Django admin (Grappelli or standard), other widgets
that load their own jQuery (like PrettyJSONWidget, JSONEditor, django-summernote, etc.)
can overwrite the global jQuery variable.

Since django_select2.js currently prefers jQuery over window.django.jQuery: ```javascript factory(jQuery || window.django.jQuery)

It uses the newly loaded jQuery instance which doesn't have Select2 attached, causing: $element.select2 is not a function

Solution

Reverse the preference order to use Django's protected jQuery instance first: factory(window.django.jQuery || jQuery)

This ensures Select2 functionality works regardless of what other widgets do to the global jQuery variable.

Related

This complements Fix #292 which ensures proper JS media loading order. That fix controls django-select2's own loading order, but can't prevent third-party widgets from loading jQuery afterward.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 48.73%. Comparing base (f61b09c) to head (6b63c54).
⚠️ Report is 54 commits behind head on main.

❗ There is a different number of reports uploaded between BASE (f61b09c) and HEAD (6b63c54). Click for more details.

HEAD has 12 uploads less than BASE

Flag	BASE (f61b09c)	HEAD (6b63c54)
	13	1

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #354       +/-   ##
===========================================
- Coverage   98.21%   48.73%   -49.48%     
===========================================
  Files           7        7               
  Lines         280      277        -3     
===========================================
- Hits          275      135      -140     
- Misses          5      142      +137     

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[codingjoe]

Hi @marcelo-maldonado95 👋,

intersting… yes, that is the better default. Let's ship it!

Best,
Joe

[Digenis]

django doesn't vendor jquery in the default setup
but in django.contrib.admin
so wherever django's jquery is mentioned, it's actually django admin's jquery.

window.django is undefined when the django admin app is not enabled
and this release breaks such django setups.

So the selection syntax, even before this PR,
should have anticipated an undefined window.django:
window.django?.JQuery || JQuery, or, for older browser compatibility,
window.django && window.django.JQuery || JQuery

This is enough to fix setups without django admin enabled
which is probably the majority of setups broken by 8.4.4.

I think the above notes should be enough to justify another bugfix release.

---

I separate these notes because I didn't reach a conclusion or a suggestion.

I agree with this PR that django_select2 shouldn't rely on the global jquery by default
and even those 3rd party widgets mentioned also shouldn't
but they are not the only ones including jquery.
E.g. since I don't use django admin
I pull it from npm and deliver it using the staticfiles app
and I'm probably not the only one.

For anyone using at the same time django admin
and select2 with a different jquery build
the above suggestion in the previous section doesn't fix it.

Any automatic choice is fragile.
Allowing multiple namespaces for jquery
creates a problem similar to a dependency hell.

I can't think off the top my head of a clean way to add a setting for the choice of namespace
and I can't tell if it's worth the effort.

[codingjoe]

Thanks @Digenis excellent point. Sorry that I missed that. I released a patch using optional chaining. It's baseline "widely available", I don't see an issue with that.

---

Hm… I'd love to switch to something that uses ESM dependencies. Sadly, Select2 doesn't see many updates these days. If you have an idea for another library or want to co-author one, please let me know.