tomevault-io JavaScript patterns
Default assumption: a project running on the current Node.js Active LTS (Node 24, "Krypton") or a modern browser baseline. If the project also uses TypeScript, the type-aware skill applies on top of these language patterns. Adapt advice to the Node version in the project's .nvmrc, .tool-versions, or engines field in package.json.
Severity rubric
failure: a concrete defect or violation that should not ship.warning: a smell or pattern that compounds with other findings.info: a hardening opportunity or note, not a defect.
Reference files
| File | Covers |
|---|---|
| reference/modules.md | ESM and CJS, package.json "type", dynamic import(), dual-package hazard |
| reference/syntax.md | Modern syntax: optional chaining, nullish coalescing, logical assignment, at() |
| reference/async.md | async/await, Promise.*, for await...of, top-level await |
| reference/errors.md | Error subclasses, Error.cause, unhandled rejection, using (advisory) |
| reference/equality-and-numbers.md | ===, Number.isNaN, Array.isArray, IEEE 754, BigInt |
| reference/collections.md | Map, Set, WeakMap, WeakSet and when to reach for each |
| reference/jsdoc.md | // @ts-check plus JSDoc tags for editor-checked types in .js files |
| reference/anti-patterns.md | Twelve review-time anti-patterns with severity calls |
When to load this skill
- Any task touching
.js,.mjs,.cjs, or.jsxfiles. - Any task involving
package.json, npm / pnpm / yarn / bun workflows, or Node runtime configuration. - Code review where the diff includes module structure, async control flow, or error handling in JavaScript.
- Migrations between ESM and CJS, or between Node major versions.
When not to load this skill
- TypeScript projects that already load type-aware patterns (this skill still applies for the language-level rules, but
any-vs-unknown, generics, and tsconfig live elsewhere). - Projects with no JavaScript surface (pure backends in another language).
References
- MDN JavaScript reference: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference
- Node.js packages: https://nodejs.org/api/packages.html
- Node.js ESM: https://nodejs.org/api/esm.html
- Node.js process: https://nodejs.org/api/process.html
- Node.js previous releases (LTS schedule): https://nodejs.org/en/about/previous-releases
- TC39 proposals: https://github.com/tc39/proposals
- 2ality (Axel Rauschmayer): https://2ality.com/
- You Don't Know JS, 2nd ed. (Kyle Simpson): https://github.com/getify/You-Dont-Know-JS
Maintenance note
ECMAScript ships a new edition each June. New syntax tends to land in V8 and Node within a release cycle of being standardized; TC39 stage 3 proposals can sometimes land in Node behind a flag before reaching stage 4. When new syntax appears in a code review, check this skill against the current MDN page and the current Node Active LTS before relying on legacy guidance here. Dropping support for an older Node major in engines.node is a breaking change for downstream consumers; treat it as such.
Source: ku5ic/dotfiles — distributed by TomeVault.