From reading the documentation, my interpretation is that it is expected that we place a visible link to the _javascript_ licensing table web page that users can see and follow, but line 28 of externalLicenseChecker.js says:
let link = document.querySelector(`link[rel="jslicense"], link[data-jslicense="1"], a[rel="jslicense"], a[data-jslicense="1"]`);
This suggests that we are also allowed to pass LibreJS tests by using an invisible link to the Web Labels page as in
<link rel="jslicense" href="" /> instead of a visible anchor link. Note that this is not personally ideal to me, but some projects have their own reasons for doing it and are experiencing an annoying bug in some cases of
doing so.
If even your own Web Labels page itself loads _javascript_ as part of the site's theme, then your Web Labels page needs to link to itself recursively with the
rel="jslicense" if I understand correctly. Doing this with the LINK element under HEAD causes LibreJS to lock Firefox 60.3.0esr into an endless loop and need a SIGTERM. There is no infinite loop when placing the LINK reference inside the BODY tags
or when using the visible <A HREF=""> method.