Frontend System Design Essentials: Client Schema Drift Explained

👉 Frontend System Design Essentials — Course: https://icodeit.thinkific.com/courses/frontend-system-design-essentials

👉 Frontend System Design Essentials — Book: https://leanpub.com/frontend-system-design-essentials/

We spend a lot of time on backend API contracts, database migrations, and backward compatibility.

But there is a hidden data store we often change without enough thought: localStorage.

When you change the shape of data in the browser, that is a schema change — except you cannot run one migration for every user device, and you cannot undo a value once it is written.

In this video I recreate a real production failure using a board app. A simple assignee-filter feature goes from a CSV string to a JSON object. The deploy looks fine. The rollback looks fine. The app can still be broken.

00:00 localStorage is a schema change
01:21 About the channel
01:37 The feature — Version 1 (CSV)
03:32 Changing the format — Version 2 (JSON)
05:45 Why this is easy to miss
06:23 Rollback failure — old code, new data
08:27 A better mental model
09:14 How to make it safer
09:24 Pattern 1 — Defensive reading
10:51 Pattern 2 — Version tag
12:14 Pattern 3 — Key versioning
13:23 Summary

📘 MY BOOKS & COURSES

👉 Frontend System Design Essentials (Course): https://icodeit.thinkific.com/courses/frontend-system-design-essentials
👉 Frontend System Design Essentials (Book): https://leanpub.com/frontend-system-design-essentials/
👉 React Anti-Patterns (Amazon): https://www.amazon.com/dp/1805123971
👉 More Tutorials on Advanced Patterns: https://icodeit.com.au/tutorials/advanced-network-patterns-react

📩 STAY CONNECTED

🧠 Newsletter (system design & clean code): https://juntao.substack.com
🌐 Website & Blog: https://icodeit.com.au
🐦 Twitter / X: http://twitter.com/JuntaoQiu
📺 YouTube (subscribe): https://www.youtube.com/@icodeit.juntao

---

#frontend #systemdesign #localStorage #webdevelopment #react #frontendarchitecture #deployment #rollback #seniordeveloper

Видео Frontend System Design Essentials: Client Schema Drift Explained канала I Code It