TypeScript Best Practices

Posted on January 5, 2025

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TypeScript adds static typing to JavaScript, helping catch errors early and improving code maintainability. Here are some best practices for TypeScript development.

Enable Strict Mode

Always use "strict": true in your tsconfig.json. This enables all strict type-checking options and helps catch potential bugs at compile time.

{
  "compilerOptions": {
    "strict": true,
    "noImplicitAny": true,
    "strictNullChecks": true
  }
}

Define Interfaces for Objects

Use interfaces to define the shape of objects. This provides clear contracts and enables better autocomplete in your IDE.

interface User {
  id: string;
  name: string;
  email: string;
  role: 'admin' | 'user';
}

Leverage Union Types

Union types allow a value to be one of several types. They're particularly useful for handling different states or variants.

type Status = 'pending' | 'success' | 'error';
type Result = { status: 'success'; data: any } | { status: 'error'; error: string };

Use Type Guards

Type guards help TypeScript narrow down types within conditional blocks, improving type safety.

function isString(value: unknown): value is string {
  return typeof value === 'string';
}

Avoid the Any Type

The any type defeats the purpose of TypeScript. Use unknown for truly unknown types, and narrow them down with type guards.

Utility Types

Leverage TypeScript's built-in utility types like Partial, Required, Pick, and Omit to transform types.

type PartialUser = Partial;
type UserWithoutEmail = Omit;

Generic Constraints

Use generic constraints to ensure type parameters meet certain requirements.

function getProperty(obj: T, key: K): T[K] {
  return obj[key];
}

Conclusion

Following these TypeScript best practices will help you write more robust and maintainable TypeScript code. The initial learning curve pays off with fewer runtime errors and better developer experience.