Option vs vanilla strict null checking

foo.ts

// findPersonWithName = string => Person | undefined;
// findParentForPerson = Person => Person | undefined;
// isOver50 = Person => boolean;
// isSubscribed = Person => boolean;

// Without Options
// In TS1 this is not type safe, in TS2 it is
const person = findPersonWithName('bob')
const parent = person !== undefined ? findParentForPerson(person) : undefined;
const parentOver50 = parent !== undefined ? (isOver50(parent) ? parent : undefined) : undefined;
const parentIsSubscribed = parentOver50 !== undefined ? isSubscribed(parentOver50) : undefined;
const isBobParentSubscribed = parentIsSubscribed !== undefined ? personIsSubscribed : false;

// Options
const isBobParentSubscribed = findPersonWithName('bob')
    .flatMap(findParentForPerson)
    .filter(isOver50)
    .map(isSubscribed)
    .getOrElse(false)

notes.md

• Both equally as type safe in TS2
• Chaining of Option is convenient and makes for concise code
• Isolating null checks in Options means you're safe from coercion errors (e.g. const x = 0; const derivedY = x ? x + 1 : 1;—x is falsy)
• Option forces you to handle failure case