Advanced TypeScript Patterns

Production-grade TypeScript patterns for building type-safe, maintainable, and scalable applications. This skill covers generics, utility types, conditional types, discriminated unions, branded types, and more.

1. Advanced Generics with Constraints

Basic Generic Constraints

// Constrain T to objects that have a .length property
function getLength<T extends { length: number }>(item: T): number {
  return item.length;
}

getLength("hello");       // OK - string has .length
getLength([1, 2, 3]);     // OK - array has .length
// getLength(42);          // Error - number has no .length