TypeScript · Middle · Question 56 of 75

Why might `Readonly<Settings>` not prevent this change?

const s: Readonly<Settings> = load();
s.theme.colors.primary = 'red';

✓Correct answer: Readonly is shallow; nested objects stay mutable
2Readonly works only on arrays
3Assignments to nested properties are always allowed in TS

Explanation

A recursive DeepReadonly type or as const for literals protect nested levels at the type level.

Further reading

TS: Utility Types ↗

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