LowFile-scopeJavaScript / TypeScript Plug & play

Hoist or cache expensive computations

Hoist constant work (e.g., RegExp, static JSON, config loads) out of loops and cache results by input when feasible.

Why this matters

Avoids unnecessary CPU and GC pressure.

Side-by-side examples engineers can pattern-match during review.

Avoid

for (const s of strs){ const re=new RegExp(pattern); re.test(s); }

Prefer

const re=new RegExp(pattern); for (const s of strs){ re.test(s); }

Bad

new RegExp(...) inside the loop

Good

declare the regex once outside the loop

From the same buckets as this rule.

Critical
Avoid Blocking Calls to Async Methods
Blocking async methods with `.Result` or `.Wait()` can cause deadlocks and prevent efficient asynchronous execution. Use `await` instead for proper async behavior.
concurrency-safetyperformance-efficiency
Critical
Fingerprint assets and cache immutably
All static JS/CSS/font/image files MUST use content-hashed filenames (e.g., app.9c1a7b.js) and be served with "Cache-Control: public, max-age=31536000, immutable". HTML and other non-fingerprinted documents MUST be served with "Cache-Control: no-cache" (or equivalent) to enable conditional revalidation.
web-static-assetscaching-strategy+2
Critical
No live network or DB in unit tests—use fakes/mocks
Unit tests must stub or fake external HTTP/DB calls; allow real I/O only in integration/e2e tests tagged accordingly.
testing-qualityperformance-efficiency+1