Svelte · Middle · Question 9 of 75

Why doesn't `items.set(k, v)` update the UI when `items` is a plain `Map` in `$state`?

✓Correct answer: $state only proxies plain objects and arrays; use SvelteMap from svelte/reactivity
2Maps can't be used in Svelte
3You must call $state.update(items)

Explanation

svelte/reactivity also has SvelteSet, SvelteDate, SvelteURL, SvelteURLSearchParams and MediaQuery. Their values aren't made deeply reactive.

Why doesn't `items.set(k, v)` update the UI when `items` is a plain `Map` in `$state`?

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Why doesn't items.set(k, v) update the UI when items is a plain Map in $state?

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Test yourself

Why doesn't `items.set(k, v)` update the UI when `items` is a plain `Map` in `$state`?