TypeScript Best Practices for Large Projects

Essential TypeScript practices and patterns for maintaining large-scale applications

• 10 min read
TypeScriptJavaScriptBest Practices

TypeScript has become the go-to choice for large-scale JavaScript applications. Here are essential practices for maintaining complex TypeScript projects.

Type Organization

Custom Type Utilities

type Nullable<T> = T | null;
type Optional<T> = T | undefined;
type Required<T> = {
  [P in keyof T]-?: T[P];
};

Advanced Types

Discriminated Unions

type Success<T> = {
  type: 'success';
  data: T;
};

type Error = {
  type: 'error';
  error: string;
};

type Result<T> = Success<T> | Error;

Project Structure

src/
  types/
    common.ts
    api.ts
  utils/
    type-guards.ts
  services/
    api.service.ts

Type Guards

function isSuccess<T>(result: Result<T>): result is Success<T> {
  return result.type === 'success';
}

Remember:

  • Keep types close to their usage
  • Use strict mode
  • Leverage type inference
  • Document complex types