Svelte · Senior · Question 3 of 75

How are `$derived` values evaluated?

✓Correct answer: Lazily and memoized: recalculated only when read after a dependency changed, and downstream updates are skipped if the result is the same
2Eagerly on every state change, even if nobody reads them
3Once per animation frame

Explanation

Svelte uses push-pull reactivity: changes mark dependents dirty (push), values are recomputed on read (pull). Equal results don't propagate.

Further reading

Svelte: $derived ↗

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