Great explanation, trying to learn regex as well, could you explain '$1 ' as well? I've seen some explanations but I am not fully sure how to interpret and your prior explanation cleared things up for the first part of the statement. Thanks!

usually that means you've exited out before the submit tests could be run, if you post your solution below and mark it as a spoiler I can tell you why. :)

EDIT: Oh I see what you mean... I'll fix that up.

regexr is a good site to practice on. It has all the regexr's for javascript including $.

This test is testing a new log line. It tests that the message part of this line is "We have a problem"

For info the log line is:
"2003-07-08 16:49:46,896 INFO [user1:mainfunction:thing] We have a problem"

Good luck finding overoptimized code in the vanilla JS.

Ok, fixing it right now! If the example test cases are fixed, please mark this issue as resolved. Thank you :)

@sensir: In any decent RegEx tutorial, for example ŧhe one on MDN.

Where can I get more info on that '$' at the end of the regex? I didn't know about that one and I don't seem to find it.

Good point. I added an example test. And I switched the expected, results arguments in assertEqual.

Hmm it's wrong ! Looks like the sesei have jumbled the test cases.

Test.assertEquals(actual, expected, msg);
Test.assertSimilar(actual, expected, msg);
                      
actual = Users Answer  &  expected = Correct Answer

take While means you take items while condition is true.
So :

takeWhile([ 1, 4, 2, 3, 5, 4, 5, 6, 7 ], isEven ) // -> [] 'cause 1 is not even
... or 
takeWhile([ 2, 1, 2, 4, 3, 5, 4, 6, 7, 8, 9, 0 ], isOdd ) // -> [] 'cause 2 is not odd

think issue shoould be marked solved

/!\ "Quick & dirty" rather than "Best practice" /!\

Sorry about that. I've modified the TCs.