Reference

sessionStorage integration checklist

60-second design-review scan. Print-friendly. Pair with lesson 3.

Lesson 3 Lesson 4 Playbook API sheet Glossary Mission

Fit?

☐ Small string / JSON only (not bulk entities)
☐ Lifetime is this tab’s page session (reload OK; die on close OK)
☐ Isolation is a feature (parallel tabs must not share this state)
☐ Main-thread only; no worker/service-worker ownership of the data
☐ Not secrets / access tokens (XSS-readable)

If not fit, prefer…

Need	Prefer
Survive close + share all tabs	`localStorage` (tiny) or server preference
Structured / large / offline	IndexedDB
HTTP shell / assets offline	Cache API (+ SW)
File-shaped bytes	OPFS
Multi-tab live sync	`BroadcastChannel` / `localStorage` events / server — not sessionStorage
Re-fetch is cheap	Memory only

Implementation hygiene

☐ storageAvailable("sessionStorage") probe (try set/remove) before relying on it
☐ Methods only: getItem / setItem / removeItem
☐ JSON.stringify / parse with null guards
☐ try/catch on writes → handle QuotaExceededError
☐ No hot-path thrash (input every keystroke without debounce → jank)
☐ Don’t expect storage events on other tabs for session writes
☐ Know opener copy: window.open starts with a copy, then diverges

Security / product

☐ No long-lived tokens in Web Storage
☐ Clearing site data / “block cookies” can disable storage — degrade gracefully
☐ Private/incognito: still works until window closes; don’t promise durability