The Lovelace UI is a customizable interface. With additional community plugins you can extend the default Lovelace experience.
Lovelace Plugin download location
All the Lovelace Plugins you download with HACS is stored in
www/community/ in your Home Assistant configuration directory.
Special notes about downloaded Lovelace Plugins
.js file is downloaded, a compressed
.gz version of if will be created, this file (if it exist) will be served to the requester to save transfer size/time.
If you make local changes to a plugin in the
.js file, delete the
.gz variant to have HACS serve up that one.
At the bottom of every page for plugins it will state how you should add it to your Lovelace configuration.
Custom view (/community_plugin)
HACS have a custom view/path/endpoint for serving up Lovelace elements (plugins)
/community_plugin/, this works mostly the same way as
/local but have some extra features.
/community_pluginendpoint does not have cache issues, it will instruct your browser to fetch a new version on each load.
/community_pluginendpoint will try to serve a .gz variant of the element, this will make the element smaller and the transfer will be faster.
Your plugin exist in
www/community/plugin/plugin.js you can use both
/community_plugin/plugin/plugin.js to reference it, but only the
community_plugin version will have the extra features that HACS offers.
.gz example, CCH (Compact Custom Header) is a fairly popular element for Lovelace, when you use
/local you will transfer the
.js file with it's 101kB, if you use HACS and
/community_plugin for it, it will give you the
.gz version atuomagically and that is only at 20kB (sizes was for version 1.4.7 of CCH).
Open plugin button
Every plugin you have installed with HACS will have a "Open pluign" button. This is useful to use while troubleshooting, if you can see a code wall everything is OK.
if you get a 404 try reinstalling it.