Last modified: 2014-10-31 00:06:21 UTC
The new awesome HTML API output displays: uselang ... A list of codes may be fetched from action=query&meta=siteinfo&siprop=languages The displayed query string is correct -- https://www.mediawiki.org/w/api.php?action=query&meta=siteinfo&siprop=languages would work. But the link in the HTML here is to <a href="/w/api.php?action=help&modules=query%2Bsiteinfo">, which doesn't work, it instead generates help for meta=siteinfo. Should be an easy fix to includes/api/ApiHelp.php , patch coming...
It's actually in includes/api/i18n/en.json: apihelp-main-param-uselang": "Language to use for message translations. A list of codes may be fetched from [[Special:ApiHelp/query+siteinfo|action=query&meta=siteinfo&siprop=languages]] so it's intentionally linking to more help (ApiHelp.php does a "Replace Special:ApiHelp links with links to api.php"), rather than executing the displayed API query as I expected. The latter seems more useful.