Loading this page executes some simple automated javascript tests of the Sling client library.
Note that you need to login before running these tests.
If all goes well, the paragraph styled like this below should say "Done running tests".
Tests run quickly, this might have happened already.
To run the tests again click here.
After running the tests at least once, /sling-test/testhtml-nodes.json should show the JSON data of the nodes created by the test cases.
See the source code of this page for details.