null & undefined

When strict null checks are on, null and undefined must be handled explicitly. This helps you avoid crashes from missing values:

function greet(name: string | null) {
  if (name === null) return "Hello, guest!";
  return `Hello, ${name}!`;
}

Key operators for handling maybe-values:

Nullish coalescing – value ?? defaultValue (fallback for null/undefined)
Optional chaining – user?.address?.city (safe nested property access)

const displayName = user.name ?? "Anonymous";
const city = user?.address?.city;

In this category, you'll:

Handle null and undefined with explicit checks
Use ?? for clean default values
Use ?. to safely access nested properties
Distinguish between nullish values and falsy values (0, "", false)

Best practice: Prefer small, clear checks. Don't rely on general truthy/falsy rules when you specifically want to treat null or undefined as missing.

Greet Maybe Name

Safe Length

Normalize Email

First Defined

Get City Label

Sum Prices Safely