The LETTERS constant could be inside the findMissing function... but that seemed less reusable. Covers all the test cases and should only iterate the arrays fully if there is no missing character to be found. So should be pretty fast as well.
For further actions, you may consider blocking this person and/or reporting abuse
We're a place where coders share, stay up-to-date and grow their careers.
Here is another JS version
The LETTERS constant could be inside the findMissing function... but that seemed less reusable. Covers all the test cases and should only iterate the arrays fully if there is no missing character to be found. So should be pretty fast as well.