Client-side JavaScript is always distributed[1] source[2] code - because your web page is distributing it to the user's browser. So AFAIK you shouldn't use GPL nor LGPL code in your pages unless all your client-side JavaScript in the page is appropriately licenced. Minified or obfuscated is still source code (you must provide original source as per license).

Client-side LGPL JavaScript is neither statically linked nor dynamically linked but potentially could be a "mere aggregation" i.e. it is hard to use LGPL legally. Perhaps you could meet the legal definition of calling a library by using web assembly or web workers (see your IP lawyer!).

Unfortunately the FSF appear to be intentionally vague when documenting this issue.

For more details see:

https://greendrake.info/publications/js-gpl

https://opensource.stackexchange.com/questions/4360/what-are... (be careful reading it because part of that answer is about what circumstances client-side GPL mean that the server-side should be GPLed).

This issue can affect the HTML and CSS too:

  It is possible to write Javascript code which is strongly bound to a particular HTML document. The Javascript code in this case would have hard-coded references to parts of the HTML document and would rely on that document's particular structure to work. This would be a strong indication that the Javascript and the document should be considered a single work.

Edit: [1] Well conveyed: https://www.gnu.org/licenses/gpl-faq.html#ConveyVsDistribute

Edit: [2] or object code (transpiled/minified) but distributing/conveying object code usually requires you to provde source.