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web-storage

Use when reviewing scripts, client components, bundles, or runtime behavior related to Use Web Storage API safely. Inspect both source code and the browser execution path so fixes target the real bottleneck or bug.

skills/web-storage/SKILL.md

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Last checked: Nov 9, 2026

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Repository stars (not skill ratings): 74,698
Repository last updated: Oct 31, 2026
License: MIT

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frontend Repository topic
front-end-development Repository topic
front-end-developer-tool Repository topic
guidelines Repository topic
checklist Repository topic
reference Repository topic
web-development Repository topic
html Repository topic
css Repository topic
javascript Repository topic
engineering Derived category

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SKILL.mdcore · 2,030 bytes
SKILL.mdcore · 2,030 bytes
references/rule.mddoc · 4,256 bytes

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# Use Web Storage API safely

localStorage and sessionStorage have a 5–10 MB quota per origin, and any write can throw a QuotaExceededError. Private browsing modes in some browsers disable storage entirely and throw on all writes. Applications that don't handle these errors crash silently, leaving users unable to use the app.

## Quick Reference

- Always wrap localStorage access in try/catch — storage can be full or disabled
- Serialize objects with JSON.stringify and validate on read with JSON.parse
- Never store sensitive data (tokens, passwords) in localStorage — use httpOnly cookies
- Use sessionStorage for tab-scoped data that shouldn't persist

## Check

Find all localStorage and sessionStorage accesses in this file. Check for missing try/catch, unhandled JSON parsing, and any storage of sensitive data.