JavaScript/TypeScript Conventions
Apply these conventions when JavaScript, TypeScript, Node.js tooling, or package.json is the primary workstream.
Dispatch
| $ARGUMENTS | Action |
|---|---|
| Active (auto-invoked when JS/TS work is primary) | Apply the operator contract below |
| Empty | Display the convention summary and routing guidance |
check | Verify tooling compliance only |
Reference File Index
| File | Purpose | When to Read |
|---|---|---|
references/tooling-contract.md | Required package-manager, command, CI, workspace, and package-root rules | Package commands, scripts, dependencies, lockfiles, or CI |
references/redirection-boundaries.md | When JS/TS conventions should yield to Python, shell, CI, or framework-specific skills | Mixed-language or ambiguous work |
references/edge-cases.md | Exception gates for npm/yarn, Corepack, generated apps, and migrations | Deviations from pnpm defaults |
references/typescript-patterns.md | TypeScript config, narrowing, type guards, unions, and type-test patterns | TypeScript code or tsconfig.json |
references/eslint-prettier.md | ESLint flat config, typed linting, and Prettier separation | Linting or formatting changes |
Operator Contract
Active
- Apply this skill only when JS/TS files, Node tooling, or
package.jsonare the primary surface of the task. - Read
references/redirection-boundaries.mdwhen JS/TS appears alongside Python, shell, CI, or framework-specific work. - Enforce the hard requirements in
references/tooling-contract.mdfor package management, package-root selection, command execution, lockfiles, workspaces, and CI installs. - Check
references/edge-cases.mdbefore recommending npm, yarn, global package managers, Corepack assumptions, or lockfile migrations. - Read
references/typescript-patterns.mdfor TypeScript config or type-safety changes. - Read
references/eslint-prettier.mdfor linting, typed linting, or formatting changes. - Use guided preferences only when starting new work or when the repo does not already have a stronger local convention.
Empty / Help
- Summarize the hard requirements:
pnpm,packageManager,pnpm-lock.yaml,pnpm install --frozen-lockfile,pnpm exec,pnpm dlx,tsc --noEmit,eslint, andprettier. - Show the difference between hard requirements and guided preferences.
- Point to the exact reference files for tooling, exceptions, TypeScript, lint/format, and mixed-language routing.
check
- Verify JS/TS tooling compliance only; do not widen into implementation advice unless the user asks.
- Report whether the project uses the expected package root,
pnpm,packageManager,pnpm-lock.yaml, workspace config, scripts,tsconfig.json, ESLint flat config, and Prettier. - Flag npm/yarn/Corepack/legacy deviations and require the reason to match
references/edge-cases.md. - Reject recommendations that replace repo-required tooling with
npm install,npx, or ad hoc global binaries unless an exception is documented.
Hard Requirements
- Package manager: use
pnpmfor JS/TS package operations unless an exception is documented. - Package manager pin: honor the nearest owning
package.jsonand itspackageManagerfield. - Lockfile: commit
pnpm-lock.yaml; never mix lockfiles in one package root without a migration plan. - Install: use
pnpm install; usepnpm install --frozen-lockfilein CI. - Dependencies: use
pnpm add <pkg>orpnpm add -D <pkg>from the owning package root. - Local binaries: use
pnpm exec <cmd>; usepnpm dlx <pkg>only for one-off registry execution. - Scripts: use
pnpm run <script>orpnpm --filter <pkg> run <script>. - Type checking: use
pnpm exec tsc --noEmitor the repo's package script. - Linting: use ESLint flat config for new ESLint setup.
- Formatting: use Prettier for formatting and ESLint for code-quality rules.
Guided Preferences
When starting new JS/TS work and no stronger local constraint exists, prefer these tools. These are defaults, not absolute law; check references/edge-cases.md before overriding an established project choice.
| Purpose | Tool | Notes |
|---|---|---|
| Package manager | pnpm | Pin through packageManager when the package root owns package.json |
| Bundler | vite or esbuild | Respect framework-owned builders first |
| Linting | eslint | Use flat config for new setup |
| Formatting | prettier | Keep formatting separate from linting |
| Testing | vitest or framework-native runner | Prefer existing repo scripts |
| Type checking | tsc --noEmit | Run through pnpm exec or package scripts |
TypeScript Type Safety
- Prefer
unknownoverany; do not weaken established strictness to make code compile. - Prefer
interfacefor object shapes andtypefor unions, intersections, and mapped types. - Use discriminated unions for state machines and tagged variants.
- Use
as constandsatisfiesto preserve literal inference without unsafe assertions. - Avoid type assertions (
as); prefer type guards, assertion functions, and schema validation at boundaries. - Enable
strictin new TypeScript projects and add stricter options when the repo can absorb them. - Test negative type behavior with
@ts-expect-erroror a type-test tool when type contracts are public. - See
references/typescript-patterns.mdfor TSConfig, module-resolution, and narrowing patterns.
Critical Rules
- Require
pnpmfor JS/TS dependency changes unlessreferences/edge-cases.mdjustifies npm, yarn, or another manager. - Resolve the owning package root before running package commands; do not assume the repository root owns every JS/TS file.
- Never mix
pnpm-lock.yaml,package-lock.json, andyarn.lockin the same package root outside a dedicated migration. - Run CI installs with
pnpm install --frozen-lockfilewhen apnpm-lock.yamlis present. - Use
pnpm execfor local binaries andpnpm dlxonly for one-off packages fetched from the registry. - Do not assume Corepack is bundled with the active Node.js runtime; check
references/edge-cases.mdbefore recommending Corepack setup. - Keep Prettier responsible for formatting and ESLint responsible for code-quality rules.
- Redirect mixed-language or non-JS-primary work through
references/redirection-boundaries.mdinstead of force-fitting this skill onto the whole task.
Scaling Strategy
- Incidental JS/TS file in a broader non-JS task: enforce only the hard requirements that touch the JS/TS-owned surface, then route mixed-workflow questions through
references/redirection-boundaries.md. - JS/TS-primary feature or refactor work: apply the full operator contract, including tooling, TypeScript, linting, formatting, and test guidance where relevant.
- Repo-wide JS/TS tooling or migration work: use
check,references/tooling-contract.md, andreferences/edge-cases.mdto separate hard violations from documented transition paths.
Progressive Disclosure
- Do not load every reference by default.
- Read
references/tooling-contract.mdfirst for command, dependency, package-root, workspace, lockfile, or CI questions. - Read
references/redirection-boundaries.mdwhen Python, shell, CI, infra, or framework-specific work is mixed into the request. - Read
references/edge-cases.mdonly when the task appears to require npm, yarn, Corepack setup, generated app scaffolding, or lockfile migration exceptions. - Read
references/typescript-patterns.mdonly when TypeScript code,tsconfig.json, public types, or type tests are active. - Read
references/eslint-prettier.mdonly when the task touches linting, typed linting, or formatting.
Scope Boundaries
IS for: JS/TS tooling conventions, Node package commands, dependency-management rules, TypeScript type-safety defaults, lint/format/test command guidance, and exception-aware repo guidance.
NOT for: Python conventions, shell conventions, CI pipeline design, framework architecture, backend-only implementation strategy, or broad frontend UX/design guidance.
Canonical terms (use these exactly):
pnpm-- the required package manager for JS/TS package operationspackage root-- the nearest directory whosepackage.jsonowns the command or dependencypackageManager-- thepackage.jsonfield that pins the package manager and versionpnpm-lock.yaml-- the canonical JS/TS lockfile for pnpm package rootsworkspace-- pnpm workspace declared bypnpm-workspace.yamlfrozen-lockfile-- CI install mode that prevents lockfile mutationpnpm exec-- local project binary executionpnpm dlx-- one-off package execution from the registry
Validation Contract
Before considering this skill complete after edits, run:
uv run wagents validateuv run wagents eval validate- Run the skill-creator audit command with
audit.py skills/javascript-conventions/ --format json uv run wagents package javascript-conventions --dry-runuv run wagents readme --checkgit diff --check
Completion criteria: all applicable commands must pass with zero errors, or the final response must name the exact unrelated blocker.