Optional chaining ?. and nullish coalescing ??

The two safe-access operators

These pair perfectly with the narrowing patterns from this module.

Optional chaining ?.

Short-circuits the whole chain to undefined if any intermediate is null or undefined.

user?.address?.zipCode;         // undefined if user or address is null
user?.greet?.();                // calls greet only if it exists
arr?.[0];                       // arr[0] only if arr is non-null

Nullish coalescing ??

Returns the right side only if the left is null or undefined. Unlike ||, it does NOT replace 0, "", or false — those are real values you usually want to keep.

const port = config.port ?? 3000;       // 0 stays 0
const name = user.nickname ?? user.name; // empty string nickname stays

Together

The canonical "safe pick with default" pattern:

const city = order?.shipping?.address?.city ?? "Unknown";

If any link is null/undefined → "Unknown". If shipping.address.city is "" or 0 → keeps it.

|| vs ??

x || y returns y for ANY falsy x — including 0, "", false. x ?? y only for null/undefined. In configs, ?? is almost always what you want.