Just found the mistake. My regex didn't match zeros and therefore it did not recognize +10 or -10 movements correctly. Sorry, my bad.

I have already reset, there still to many tests failing

Here is another test result:

expected [ 'l', 'e', 'Q', 'I', 'z', 'f', 'P', 'O', 'm', 'h', 'U', 'w', 'E' ] to deeply equal [ 'h', 'e', 'Q', 'I', 'z', 'f', 'P', 'O', 'm', 'U', 'l', 'w', 'E' ]

leaderboardSort(["l","z","f","e","O","m","P","I","U","h","w","E","Q"], ["Q +3","Q +5","I +2","h +10","f -4","P +1","z -5","f -1","O +1","Q +0","l -10","O -5","l +1"])

There is nothing smaller sorry

does not work for me. I carefully went through all changes by hand and I know my algo spits out the correct changes to the board. Test this my result is:

assert.deepEqual(leaderboardSort(["ivy","uQV","YiJ","pBO","uhU","RHK","zJx","bhQ","pcj","LbZ","QJv","usq","uZi","KFM"], ["QJv +9","uZi +8","pcj +8","usq +7","pcj -11","usq +3","uQV -3","bhQ +7","uhU +3","LbZ +8","LbZ -10","pcj +3","ivy -9","KFM +9"]), [ 'usq',
'QJv',
'bhQ',
'KFM',
'YiJ',
'uhU',
'uZi',
'pBO',
'uQV',
'pcj',
'ivy',
'RHK',
'zJx',
'LbZ' ]);

Result : [ 'pcj',
'QJv',
'usq',
'bhQ',
'KFM',
'LbZ',
'YiJ',
'uhU',
'uZi',
'uQV',
'pBO',
'ivy',
'RHK',
'zJx' ]