The API help shown by Special:ApiHelp and `action=help` includes example API requests. For example [[ https://www.mediawiki.org/wiki/Special:ApiHelp/query | Special:ApiHelp/query ]] has this example
[[ https://www.mediawiki.org/w/api.php?action=query&prop=revisions&meta=siteinfo&titles=Main%20Page&rvprop=user%7Ccomment&continue= |api.php?action=query&prop=revisions&meta=siteinfo&titles=Main%20Page&rvprop=user%7Ccomment&continue=]]
which you can click to see the API response.
This is great but if you want to modify parameters it is fiddly to modify the browser URL. If the wiki has Extension:ApiSandbox it would be nice to provide an extra link "Load this example API request into Special:ApiSandbox".
ApiSandbox supports this \o/ , its `doHash()` function applies anything in the URL fragment (after the hash mark) to its UI. So take the example URL query string, and append it to Special:ApiSandbox# and we get the desired behavior:
https://www.mediawiki.org/wiki/Special:ApiSandbox#action=query&prop=revisions&meta=siteinfo&titles=Main%20Page&rvprop=user%7Ccomment&continue=
I'll try to add something similar to [[ https://www.mediawiki.org/wiki/Template:ApiEx | Template:ApiEx ]].