typescript_skill

Overview

This skill helps configure and enforce TypeScript conventions, tooling, and common patterns across a project. It focuses on safe typing, consistent ordering, formatting and linting choices, and recommended libraries for common tasks like date handling. Use it to get a predictable, maintainable TypeScript codebase.

How this skill works

The skill inspects project files for TypeScript usage (.ts/.tsx), linting configs, and missing type definitions. It recommends or creates configurations (Biore/biome.jsonc when appropriate), applies rules such as avoiding any, preferring type aliases, and enforcing alphabetical ordering for fields and parameters. It also suggests using dayjs for date logic and provides style guidance like centered comment dividers.

When to use it

• Setting up TypeScript in a new or existing project
• Fixing or preventing type errors and missing definitions
• Converting JavaScript files to TypeScript (.ts/.tsx)
• Adding a consistent linter/formatter or creating biome.jsonc
• Implementing date/time logic and preferring dayjs

Best practices

• Never use the any type; prefer explicit types and generics
• Prefer type aliases (type) over interface for declarations
• Keep object keys, type fields, function parameters, and class properties alphabetized
• Use BiomeJS for formatting/linting unless the project already uses ESLint + Prettier
• Use dayjs for date and time calculations instead of the native Date
• Avoid returning values from forEach callbacks; use map/filter/reduce when transforming

Example use cases

• Add TypeScript and tsconfig to a JavaScript project and convert key modules to .ts/.tsx
• Replace uses of isNaN with Number.isNaN and fix related type checks
• Introduce dayjs for deadline calculations and timezone-agnostic comparisons
• Create biome.jsonc for consistent formatting and integrate with CI
• Refactor a codebase to remove any types and add accurate type aliases