TypeScript Cheat Sheet

This quick reference guide covers common TypeScript types, built-in utility types, and typical configurations for daily use.

1. Type Annotations Quick Guide

Here is a quick look at defining standard structures:

// Primitive Types
const message: string = "hello";
const score: number = 42;

// Array Types
const list: number[] = [1, 2, 3];
const names: Array<string> = ["Alice", "Bob"];

// Tuple Types
const coordinates: [x: number, y: number] = [100, 200];

// Union Types
const input: string | number = "test";

2. Interface vs. Type Alias Comparison

// Object Structure (Either interface or type alias works)
interface Person {
  name: string;
}

type Employee = {
  id: number;
};

// Combining Shapes
interface Manager extends Person {
  department: string;
}

type Director = Person & Employee & {
  level: number;
};

3. Built-in Utility Types

interface User {
  id: string;
  name: string;
  email: string;
}

// Make all properties optional
type UpdateUser = Partial<User>;

// Make all properties mandatory
type FullUser = Required<UpdateUser>;

// Make all properties read-only
type ReadonlyUser = Readonly<User>;

// Pick select properties
type SimpleUser = Pick<User, "name" | "email">;

// Remove select properties
type SecureUser = Omit<User, "id">;

4. Compiler Settings Cheat Sheet

Use these core compiler options in your tsconfig.json file:

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "NodeNext",
    "moduleResolution": "NodeNext",
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true
  }
}

Keep "strict": true enabled to catch the maximum number of potential issues during compilation.