TypeScript Best Practices

Name: Typescript Practice
Rating: 76
Author: mizchi

Principles

•Prefer standard library over external dependencies
•Avoid classes; use pure functions and separate state
•Keep functions idempotent

Package Manager

Use pnpm unless package-lock.json exists:

bash

pnpm install
pnpm add <package>

Bundler

•Frontend: vite
•Library: tsdown

Lint

Use oxlint (fast, Rust-based):

bash

pnpm add -D oxlint
pnpm oxlint

See assets/oxlint.json for config example.

Execution

Node.js 24+ runs TypeScript directly without flags:

bash

node foo.ts

Testing

Use vitest:

bash

pnpm add -D vitest

typescript

// foo.test.ts
import { expect, test } from 'vitest';
import { add } from './foo.ts';

test('add', () => {
  expect(add(1, 2)).toBe(3);
});

bash

pnpm vitest

Code Style

typescript

// Good: pure function + separate state
type State = { count: number };

const increment = (state: State): State => ({
  ...state,
  count: state.count + 1,
});

// Avoid: class with mutable state
class Counter {
  count = 0;
  increment() { this.count++; }
}

Prefer Standard APIs

typescript

// Good: native fetch
const res = await fetch(url);
const data = await res.json();

// Good: native crypto
const id = crypto.randomUUID();

// Good: native URL
const url = new URL('/path', base);