30 Days of Code is a coding challenge created by HackerRank to help people learn how code and/or brush up on their core programming skills. Each day a new challenge is unlocked in addition to a corresponding video to help explain.
The challenge allows a number of programming languages where applicable. (For this, JavaScript is not eligible for class-based challenges given its inherent prototype-based model.) Topics include if-else statements, recursion, data structures and more.