writing-typescript

Q: How do I install writing-typescript?

Run npx skills add https://github.com/julianobarbosa/claude-code-skills --skill writing-typescript in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/writing-typescript/ (personal) or .claude/skills/writing-typescript/ (project).

by julianobarbosaCode Quality & Workflow

Idiomatic TypeScript development. Use when writing TypeScript code, Node.js services, React apps, or discussing TS patterns. Emphasizes strict typing, composition, and modern tooling (bun/vite).

Installs: 110
Last 24h: —
Trending rank: —
Security: Not audited

Install

Works with every agent the skills CLI supports.

npx skills add https://github.com/julianobarbosa/claude-code-skills --skill writing-typescript

01
Install
Run the command in your project. The CLI asks which agents to install for.
02
Describe the task
Ask your agent for something this skill covers. It loads writing-typescript automatically when relevant.
03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.

SKILL.md

The instructions your agent reads when the skill is triggered.

TypeScript Development (2025)

Core Principles

Strict typing: Enable all strict checks
Parse, don't validate: Transform untrusted data at boundaries
Composition over inheritance: Small, focused functions
Explicit over implicit: No any, prefer unknown

Toolchain

bun          # Runtime + package manager (fast)
vite         # Frontend bundling
vitest       # Testing
eslint       # Linting
prettier     # Formatting

Quick Patterns

Type Guards

function isUser(value: unknown): value is User {
  return typeof value === "object" && value !== null && "id" in value;
}

Discriminated Unions

type Result<T, E = Error> = { ok: true; value: T } | { ok: false; error: E };

function processResult<T>(result: Result<T>): T {
  if (result.ok) return result.value;
  throw result.error;
}

Utility Types

type UserUpdate = Partial<User>;
type UserSummary = Pick<User, "id" | "name">;
type UserWithoutPassword = Omit<User, "password">;
type ReadonlyUser = Readonly<User>;

tsconfig.json Essentials

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "ESNext",
    "moduleResolution": "bundler",
    "strict": true,
    "noUncheckedIndexedAccess": true,
    "exactOptionalPropertyTypes": true,
    "noImplicitReturns": true,
    "isolatedModules": true
  }
}

References

PATTERNS.md - Code patterns and style
REACT.md - React component patterns
TESTING.md - Testing with vitest

Commands

bun install              # Install deps
bun run build            # Build
bun test                 # Test
bun run lint             # Lint
bun run format           # Format

Gotchas

import type with verbatimModuleSyntax and named exports: type-only import of a value triggers errors. Fix: import { type Foo } from "mod" (inline marker).
as const on object: readonly AND literal-narrowed — different from as Foo (asserts type) or satisfies Foo (validates without widening).
satisfies validates without widening; as widens — using as where you wanted satisfies loses literal types silently.
Array<T>.includes(x) requires x to be of type T — narrowing-from-union doesn't work; the standard fix is a type-predicate helper.
strictNullChecks: false makes T mean T | null | undefined for ALL types — partial migrations leave types that lie about nullability.
tsconfig.json extends doesn't recursively merge compilerOptions.paths — child paths REPLACE parent paths, not merge.

FAQ

What does the writing-typescript skill do?

Idiomatic TypeScript development. Use when writing TypeScript code, Node.js services, React apps, or discussing TS patterns. Emphasizes strict typing, composition, and modern tooling (bun/vite).

How do I install writing-typescript?

Run npx skills add https://github.com/julianobarbosa/claude-code-skills --skill writing-typescript in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/writing-typescript/ (personal) or .claude/skills/writing-typescript/ (project).

Which AI agents can use writing-typescript?

Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.

Is writing-typescript safe to install?

No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.

Who maintains writing-typescript?

It is published by julianobarbosa in julianobarbosa/claude-code-skills. It has 110 recorded installs.