Format a duration in JavaScript
JavaScript interview exercise on Practical, difficulty 2 of 3. Solve it in the editor beside a worked example; the tests run the moment you do.
Write formatDuration(seconds) that returns "h:mm:ss" (hours unpadded, minutes and seconds two digits).
Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Progress is saved in your browser, and in your account if you sign in.