Typescript Best Practices

What the source does

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• NetworkNone observedNo outbound calls in the source
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Five audit layers

Gates applied: no behavioural pass.

Audit 0.4.1 · source sha 6f5be687a268 · 14 Oct 2026Report an issue or request a re-scan

• PublisherHoangNguyen0403 GitHub userOwner of the repository this skill is read from
• Source folderHoangNguyen0403/agent-skills-standard/.codex/skills/typescript/typescript-best-practicesThe exact folder we audited
• LicenceMITAs the repository states it
• Commit pinned for this verdict6f5be687a268A new audit runs when the source changes
• Repository statusNot archivedPushed today
• Sandboxed runNot runSkills are read, not executed; layer L4 is skipped

Its description: Write idiomatic TypeScript patterns for clean, maintainable code. Use when writing or refactoring TypeScript classes, functions, modules, or async logic.

---
name: typescript-best-practices
description: Write idiomatic TypeScript patterns for clean, maintainable code. Use when writing or refactoring TypeScript classes, functions, modules, or async logic.
metadata:
  triggers:
    files:
    - '**/*.ts'
    - '**/*.tsx'
    keywords:
    - class
    - function
    - module
    - import
    - export
    - async
    - promise
---
# TypeScript Best Practices

## **Priority: P1 (HIGH)**

## Implementation Guidelines

- **Naming**: Use **`PascalCase`** for Classes/Types/Interfaces, **`camelCase`** for variables/functions, and **`UPPER_SNAKE`** for static constants.
- **Functions**: Use **`arrow functions`** for callbacks/logic; **`function declaration`** for top-level exports. Always type **`public API`** returns.
- **Modules**: Use **`Named exports`** ONLY to enable better refactoring/auto-imports.
- **Async**: Use **`async/await`** with **`Promise.all()`** for parallel execution. Implement **`try-catch`** for error handling; type **`catch(e) as unknown`** and narrow before use. Avoid **`.then().catch()`** chains.
- **Classes**: Explicitly use **`private`**, **`protected`**, and **`public`** modifiers. Favor **`composition`** over inheritance and **`dependency injection`** with **`constructor injection`** and interfaces over singletons for testability.
- **Type Safety**: Use **`never`** for exhaustiveness checks in switch-cases.
- **Optional**: Use **`optional chaining`** (`?.`) and **`nullish coalescing`** (`??`) over manual checks.
- **Imports**: Enforce **`external packages → internal modules → relative imports`** order automatically via **`eslint-plugin-import`**. Use **`import type`** for interfaces/types to ensure better tree-shaking and zero runtime overhead.
- **Validation**: Use **`Zod`** or **`Tsoa`** for runtime boundary validation.

## Anti-Patterns

- **No Default Exports**: Use named exports.
- **No Implicit Returns**: Specify return types.
- **No Unused Variables**: Enable `noUnusedLocals`.
- **No `require`**: Use ES6 `import`.
- **No Empty Interfaces**: Use `type` or non-empty interface.
- **No `any`**: Use `unknown` or specific type.
- **No Unsafe Mocks**: Cast with `jest.Mocked<T>` or `as unknown as T`.
- **No eslint-disable**: Fix root cause; never suppress warnings.

## References

See [references/examples.md](references/examples.md) for Immutable Interfaces, Exhaustiveness Checking, Assertion Functions, DI Patterns, and Import Organization.

## Canonical response anchors

When this skill applies, preserve the following domain terminology or equivalent concrete examples in the answer when relevant:
- async/await
- injection

Excerpt, first 2,634 characters of SKILL.md, verbatim from the audited commit. It is text from someone else’s repository, quoted so you can judge it before your agent reads it.

git clone https://github.com/HoangNguyen0403/agent-skills-standard
git -C agent-skills-standard checkout 6f5be687a268

Works in

1. 2026-10-14
   ✓SAFE B 89 / 100

   first audit · source 6f5be687a268

Questions about Typescript Best Practices

• github.com/HoangNguyen0403/agent-skills-standard/tree/develop/.c — the audited source at commit 6f5be687a268 and every finding aboveObserved · 14 Oct 2026

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