Gotcha: JavaScript optional chaining with function calls

Optional chaining (?.) with method calls can produce unexpected results when the method exists but returns undefined vs when the object is null.

Be aware of what optional chaining short-circuits:

// obj?.method() - safe if obj might be null
const result = user?.getName(); // undefined if user is null

// But: obj?.method doesn't call the method!
const fn = user?.getName; // Gets the function reference

// Chained: stops at first nullish
const city = user?.address?.city; // Safe

// With arrays:
const first = arr?.[0]; // Safe array access

// GOTCHA: short-circuit affects the whole chain
const upper = user?.name.toUpperCase(); 
// If user is null: undefined (short-circuits)
// If user exists but name is undefined: THROWS!

// Safer:
const upper = user?.name?.toUpperCase();

// With nullish coalescing for defaults:
const name = user?.name ?? 'Anonymous';

Optional chaining short-circuits the entire remaining property access chain when it encounters null/undefined, but only from the ?. point onward.

JavaScript/TypeScript code dealing with nullable objects