In a separate .svelte.js file I have

export let allQuestionsRune = $state([new ObjectWithStringProperty("hi")])

Then in a button onClick method in some +page file I am doing

allQuestionsRune[0].stringProperty = "new string"

Then in a separate svelte component I am referencing this exact property as such:

<p>{allQuestionsRune[0].stringProperty}</p>

Expected behavior: I see a "hi" on the screen. Then I click the button, and I should see the "hi" change to "new string".

Actual Result: I see a "hi" on the screen. And that's it. The button is not updating at all. I thought this was supposed to be reactive ... I don't get what is going on. I have verified that the onClick method is being fired correctly.

Excerpt of some svelte documentation I don't fully understand ... If $state is used with an array or a simple object, the result is a deeply reactive state proxy. ... Perhaps this is a hint ? I don't really understand this excerpt at all.

What am I missing? Why is my rune not behaving as I expect?

In a separate .svelte.js file I have

export let allQuestionsRune = $state([new ObjectWithStringProperty("hi")])

Then in a button onClick method in some +page file I am doing

allQuestionsRune[0].stringProperty = "new string"

Then in a separate svelte component I am referencing this exact property as such:

<p>{allQuestionsRune[0].stringProperty}</p>

Expected behavior: I see a "hi" on the screen. Then I click the button, and I should see the "hi" change to "new string".

Actual Result: I see a "hi" on the screen. And that's it. The button is not updating at all. I thought this was supposed to be reactive ... I don't get what is going on. I have verified that the onClick method is being fired correctly.

Excerpt of some svelte documentation I don't fully understand ... If $state is used with an array or a simple object, the result is a deeply reactive state proxy. ... Perhaps this is a hint ? I don't really understand this excerpt at all.

What am I missing? Why is my rune not behaving as I expect?

• html
• svelte
• sveltekit
• svelte-5

1 Answer 1

Class fields aren't reactive in Svelte 5. So the problem is not that the state holds and array, but that the value in the array that you try to change is an instance of a class. If it's plain JavaScript object instead, it will work.