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Get Started Free →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.
.claude/skills/thedaviddias-web-storage/SKILL.md| Test case | Without → With | Effect | Δ tokens | Δ turns |
|---|---|---|---|---|
| case-01 | ✗→✓ | ▲ Improved | -9% | 0% |
| case-10 | ✗→✓ | ▲ Improved | 11% | 0% |
| case-22 | ✗→✓ | ▲ Improved | 63% | 0% |
| case-02 | ✓→✓ | ＝ Same ✓ | 25% | 0% |
| case-03 | ✓→✓ | ＝ Same ✓ | -33% | 0% |
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.
Find all localStorage and sessionStorage accesses in this file. Check for missing try/catch, unhandled JSON parsing, and any storage of sensitive data.
Add try/catch error handling to all Web Storage operations and ensure all object values are properly serialized and deserialized.
Explain the Web Storage API, its limitations, when to use localStorage vs sessionStorage, and what data should never be stored there.
Review scripts, client components, and browser execution paths related to Use Web Storage API safely. Flag exact imports, event handlers, runtime side effects, or blocking operations that violate the rule, and state how the change should be verified in the browser.
For full implementation details, code examples, and framework-specific guidance, see references/rule.md.
Rule page: https://frontendchecklist.io/en/rules/javascript/web-storage
| Case | Status | Duration (ms) | Turns | Tokens | Tool calls | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Without | With | Δ | Without | With | Δ | Without | With | Δ | Without | With | Δ | ||
case-02 | pass→pass | 12,394 | 13,655 | +10% | 1 | 1 | 0% | 2,342 | 2,923 | +25% | 0 | 0 | — |
case-01 | fail→pass | 14,054 | 11,867 | -16% | 1 | 1 | 0% | 2,982 | 2,707 | -9% | 0 | 0 | — |
case-03 | pass→pass | 13,073 | 7,203 | -45% | 1 | 1 | 0% | 2,503 | 1,684 | -33% | 0 | 0 | — |
case-04 | pass→pass | 12,909 | 10,880 | -16% | 1 | 1 | 0% | 2,822 | 2,502 | -11% | 0 | 0 | — |
case-05 | pass→pass | 8,329 | 9,886 | +19% | 1 | 1 | 0% | 1,718 | 2,159 | +26% | 0 | 0 | — |
case-06 | pass→pass | 5,318 | 5,863 | +10% | 1 | 1 | 0% | 982 | 1,460 | +49% | 0 | 0 | — |
case-07 | pass→pass | 11,047 | 6,318 | -43% | 1 | 1 | 0% | 1,776 | 1,356 | -24% | 0 | 0 | — |
case-08 | pass→pass | 12,914 | 8,266 | -36% | 1 | 1 | 0% | 2,408 | 1,909 | -21% | 0 | 0 | — |
case-09 | pass→pass | 9,649 | 10,341 | +7% | 1 | 1 | 0% | 1,866 | 2,272 | +22% | 0 | 0 | — |
case-10 | fail→pass | 7,153 | 6,171 | -14% | 1 | 1 | 0% | 1,267 | 1,411 | +11% | 0 | 0 | — |
case-11 | pass→pass | 10,021 | 7,208 | -28% | 1 | 1 | 0% | 1,873 | 1,602 | -14% | 0 | 0 | — |
case-12 | pass→pass | 12,603 | 8,860 | -30% | 1 | 1 | 0% | 2,121 | 1,675 | -21% | 0 | 0 | — |
case-13 | pass→pass | 6,293 | 5,722 | -9% | 1 | 1 | 0% | 1,344 | 1,372 | +2% | 0 | 0 | — |
case-14 | pass→pass | 7,546 | 6,954 | -8% | 1 | 1 | 0% | 1,384 | 1,394 | +1% | 0 | 0 | — |
case-15 | pass→pass | 11,466 | 8,155 | -29% | 1 | 1 | 0% | 2,023 | 1,894 | -6% | 0 | 0 | — |
case-16 | pass→pass | 6,433 | 4,752 | -26% | 1 | 1 | 0% | 1,169 | 1,193 | +2% | 0 | 0 | — |
case-17 | pass→pass | 14,190 | 13,364 | -6% | 1 | 1 | 0% | 2,260 | 2,962 | +31% | 0 | 0 | — |
case-18 | pass→pass | 17,413 | 11,215 | -36% | 1 | 1 | 0% | 3,789 | 2,541 | -33% | 0 | 0 | — |
case-19 | pass→pass | 11,891 | 10,877 | -9% | 1 | 1 | 0% | 2,114 | 2,481 | +17% | 0 | 0 | — |
case-20 | pass→pass | 9,340 | 7,589 | -19% | 1 | 1 | 0% | 1,987 | 1,742 | -12% | 0 | 0 | — |
case-21 | pass→pass | 10,331 | 9,023 | -13% | 1 | 1 | 0% | 1,988 | 2,030 | +2% | 0 | 0 | — |
case-22 | fail→pass | 5,765 | 8,223 | +43% | 1 | 1 | 0% | 1,178 | 1,925 | +63% | 0 | 0 | — |
DecimalAI ran this skill against gemini-3.6-flash twice over the same eval suite — once with the skill loaded and once without — and compared the two runs case by case. 22 cases were attempted. The headline lift of +14 percentage points is the difference between those two pass rates over the 22 comparable cases.
Without the skill loaded, the model failed this case. With it loaded, the same prompt on the same model passed. This is one improved case from the latest verified run; every case, including any that regressed, is in the table above.
Other measured skills in the registry, with their headline benchmark lift.