Mission 2: Build a Book Collection Manager

Leonard Leong Sud Yen's Mission 2: Build a Book Collection Manager certificate

This certificate was awarded to Leonard Leong Sud Yen on 21 August 2026 for completing Mission 2, Build a Book Collection Manager, at Sigmaschool.

What that means: “I can build a collection manager that stores data in an array of objects and renders it to the page with the DOM, and explain every line of it.”

Sigmaschool is a mastery-based programme where students build real, working software instead of watching lectures. Every mission is shipped to a live URL, walked through on video, and marked by a human instructor before it counts, so a certificate here means the work was seen and defended, not just finished.