localStorage, sessionStorage and IndexedDB
Comes up in: Web fundamentals, Recruiter screen
This concept is being written. It gets the full five steps — explanation, predict, interview angle, practice with tests, and review cards. Here is exactly what it will cover, so you can study it elsewhere in the meantime.
What it covers
- sync string API vs async structured storage
- per-origin scope
- sessionStorage per tab
storageevent across tabs- IndexedDB transactions, object stores, indexes (with a wrapper library)
- never store tokens in localStorage if XSS is a risk (trade-off discussion)
Words you will know
What you will practise
- offline notes app with IndexedDB
Interview questions this answers
- Compare cookies, localStorage, sessionStorage and IndexedDB.
- Where should you store an auth token in a SPA? What are the trade-offs?
- How do you sync state between tabs?