It is an efficient solution.

Pleasure! Of course you might need a 'break' statement in some situations.

Interesting. A boolean is subtracted from a boolean?

...true = 1,
false = 0, correct?

Ahh, very interesting... took me a good while to wrap my head around this one. Javascript's sort is hard to understand at first, but powerful!

Does this mean we should be implementing our own sort algorithms in Javascript? Or does it now have a stable sort?

Nice palindrome algorithm!

Your code is very hard to read

console.log(start, end);
The value of the last fragment and the 3rd fragment are strongly hinted at in the example test cases. Plug those in first, then look at the expected results for the other tests.

Comments or descriptive variable names would make your solution much more readable.

I think renaming variables x and n makes your code less legible. Your python program may go from 3 kb to 2 kb, but is that really worth it?

zeliza has the same solution, but much more readable.

You can print(maze) to see the maze (Python).
There are a bunch of random tests probably, so your tests change each time you run your code.

Should I be using backtracking?

Love the use of the dictionary.