TypeScript Standards

Auto-loads for projects with TypeScript in their tech stack.

Metadata

Field	Value
Type	context
Applies to	typescript, nodejs, express, nestjs, nextjs, react, vue, angular, deno, bun, zod

Core Principles

Simplicity - Simple, understandable code
Readability - Readability over cleverness
Maintainability - Code that’s easy to maintain
Testability - Code that’s easy to test
DRY - Don’t Repeat Yourself

Naming Conventions

Element	Convention	Example
Variables/Functions	camelCase	`getUserById`, `isActive`
Classes/Interfaces/Types	PascalCase	`UserService`, `ApiClient`
Constants	UPPER_SNAKE_CASE	`MAX_RETRY_COUNT`
Files	kebab-case	`user-service.ts`
Interfaces	No `I` prefix	`User` not `IUser`

Code Style

// Explicit types for function parameters and return values
function getUserById(userId: string): User | undefined {
  if (!userId) {
    throw new Error("userId cannot be empty");
  }
  // implementation...
}
 
// Prefer interfaces for object shapes
interface User {
  id: string;
  name: string;
  email: string;
  age?: number;
}
 
// Type aliases for unions and primitives
type UserId = string;
type HttpMethod = "GET" | "POST" | "PUT" | "DELETE";

Best Practices

// Nullish coalescing and optional chaining
const name = user?.profile?.name ?? "Anonymous";
 
// Readonly for immutable data
interface Config {
  readonly apiUrl: string;
  readonly maxRetries: number;
}
 
// as const for literal types
const DIRECTIONS = ["north", "south", "east", "west"] as const;
type Direction = typeof DIRECTIONS[number];
 
// Prefer unknown over any
function parseJson(input: string): unknown {
  return JSON.parse(input);
}

Utility Types

type UserUpdate = Partial<User>;           // All optional
type UserPreview = Pick<User, "id" | "name">;  // Select properties
type UserWithoutEmail = Omit<User, "email">;   // Exclude properties

Zod for Runtime Validation

import { z } from "zod";
 
const UserSchema = z.object({
  id: z.string().uuid(),
  name: z.string().min(1).max(100),
  email: z.string().email(),
});
 
type User = z.infer<typeof UserSchema>;
const user = UserSchema.parse(untrustedData);

Recommended Tooling

Tool	Purpose
`pnpm` or `bun`	Package manager
`eslint`	Linting with TypeScript rules
`prettier`	Code formatting
`vitest` or `jest`	Testing framework
`zod`	Runtime validation

tsconfig.json

{
  "compilerOptions": {
    "strict": true,
    "noUncheckedIndexedAccess": true,
    "noImplicitReturns": true,
    "forceConsistentCasingInFileNames": true
  }
}

Python JavaScript