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Transformations

map​

Transform the inner value when present; otherwise return None:

Some(2).map((n) => n + 1); // Some(3)
None.map((n) => n + 1);    // None

mapNullable​

Like map, but treats a null/undefined result as None:

Some('42').mapNullable((s) => parseInt(s, 10) || null);
Some('abc').mapNullable((s) => parseInt(s, 10) || null); // None

Useful when the mapping function returns nullable values.

flatMap​

Chain options without nesting Option<Option<A>>:

const parseId = (raw: string): Option<number> =>
    Option.of(Number.parseInt(raw, 10)).filter((n) => !Number.isNaN(n));

Some('7').flatMap(parseId); // Some(7)
Some('x').flatMap(parseId); // None

filter​

Keep the value only when the predicate passes:

Some(4).filter((n) => n % 2 === 0); // Some(4)
Some(3).filter((n) => n % 2 === 0); // None
None.filter(() => true);             // None

Chaining​

Option.of(rawEmail)
    .map((e) => e.trim().toLowerCase())
    .filter((e) => e.includes('@'))
    .getOrElse(() => '[email protected]');

Each step short-circuits on None.