Mask ASCII letters
Difficulty: Easy
Replace each ASCII letter (A–Z or a–z) with #. Preserve every other code point exactly, including digits, spaces, accents, and emoji. Return the new string.
Examples
"""""Hello 42""##### 42""A_z""#_#"Constraints
0–10,000 UTF-16 code units. No case conversion or normalization.
Review lesson: JavaScript’s string modelA little nudge
Reveal one hint at a time. Give yourself a moment to try it.
Worked solution
Try your own approach first, then compare the reasoning.
Complexity
Ready when you are
Write your solution, then run it against the practice tests.
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