Level 1: Basics · Exercise 11 of 76 · Free

Palindrome check

A JavaScript exercise from Scriptdrill. Solve it with a code editor in your browser that runs your function against example and hidden tests, and it is checked the moment you submit.

The task

Return `true` when `s` reads the same forwards and backwards, looking only at letters and digits and ignoring upper and lower case. Spaces and punctuation are skipped, so `"A man, a plan, a canal: Panama"` is a palindrome. A string with no letters or digits counts as a palindrome. Letters are plain English letters.

What this exercise teaches

Normalizing before comparing keeps the check itself trivial. The class in the replace has to keep digits as well as letters: dropping digits would turn 1a2 into a and call it a palindrome.

A hint if you get stuck

Clean the string first: lowercase it and remove everything that is not a letter or a digit, for example with `replace(/[^a-z0-9]/g, "")`. Then compare it with its reverse.