For invalid inputs in input type number, the bound value (using `bind:value={val}`) is null and not undefined.

[theAnuragMishra]

Describe the bug

https://svelte.dev/docs/svelte/bind#input-bind:value
the docs here say it is undefined in the case of an empty or a invalid input. but is null in the case of an invalid input.

Reproduction

https://svelte.dev/playground/064fcdbe349a4ee2887a12ee696b5730?version=5.28.1

Logs

System Info

i m using svelte playground, svelte 5.28.1.

Severity

annoyance

[Ocean-OS]

I'm not sure if this is a documentation issue or an actual bug, since the code explicitly defaults to null for invalid inputs.

[theAnuragMishra]

I'm not sure if this is a documentation issue or an actual bug, since the code explicitly defaults to null for invalid inputs.

function to_number(value) {
	return value === '' ? null : +value;
}

my understanding of the code: it should return null for empty input and NaN for invalid inputs.
the docs mention: it should return undefined for empty and invalid inputs.
the actual behaviour: returns undefined for empty inputs but null for invalid inputs.

it's so confusing :)

[Rich-Harris]

We need to figure out what behaviour we'd ideally have here, and whether we can make that change outside of a semver major. If not, the docs will need to be updated