admin/base.html : Add block "end_of_body" for JS includes

[Thomas Güttler]

I would like to add JavaScript includes at the end of the HTML, before </body>

I created a PR which implements it:

​https://github.com/django/django/pull/13913

It is very simple:

 <!-- END Container -->
+ {% block end_of_body %}{% endblock %}
 </body> 
 </html>

[Carlton Gibson]

As per the discussion on the PR, I'd like us to establish whether this is still needed with modern browsers and defer and async &co. 🤔
(It's not a big addition, so in principle, yes, but if we can do without...)

Thomas, can I ask that you do a bit of reading around?

[Matthias Kestenholz]

I'm definitely no expert and I haven't done any measurements, but here's a chart: ​https://caniuse.com/script-defer

<script src="..." defer> seems to be enormously well supported, certainly by all browsers that are the target of Django's admin interface.

[Mariusz Felisiak]

I agree with previous comments. I don't think that we need an extra block.