Form `novalidate` attribute doesn't render when conditional (given a value)

[Rican7]

Describe the bug

Adding a novalidate attribute to a <form> element is not rendering that attribute, unless it's not conditional (no value is given).

For example, this works: <form novalidate></form>
... but this does not work: <form novalidate={true}></form>

Reproduction

Here's a minimal reproduction using the latest release of Svelte (v5.19.1):

https://svelte.dev/playground/585b8c82301d4c65bc83eeaeda119d68?version=5.19.1

Logs

System Info

System:
    OS: Linux 4.4 Ubuntu 22.04.5 LTS 22.04.5 LTS (Jammy Jellyfish)
    CPU: (12) x64 Intel(R) Core(TM) i7-8750H CPU @ 2.20GHz
    Memory: 13.48 GB / 31.74 GB
    Container: Yes
    Shell: 5.1.16 - /usr/bin/bash
  npmPackages:
    svelte: ^5.19.0 => 5.19.0

Severity

blocking an upgrade

[Rican7]

I think I see the issue!

The JS output is showing that the attribute is being set on the JS DOM object as novalidate, which is the name of the HTML attribute, but it's not the name of the DOM property. The DOM property is noValidate.

The casing there is important.

[Rican7]

I'm not an expert on this repo, but I think this could be fixed via adding a novalidate: 'noValidate' mapping here:

svelte/packages/svelte/src/utils.js

Lines 184 to 200 in 09510c8

	/**
	* @type {Record<string, string>}
	* List of attribute names that should be aliased to their property names
	* because they behave differently between setting them as an attribute and
	* setting them as a property.
	*/
	const ATTRIBUTE_ALIASES = {
	// no `class: 'className'` because we handle that separately
	formnovalidate: 'formNoValidate',
	ismap: 'isMap',
	nomodule: 'noModule',
	playsinline: 'playsInline',
	readonly: 'readOnly',
	defaultvalue: 'defaultValue',
	defaultchecked: 'defaultChecked',
	srcobject: 'srcObject'
	};

🤔

[elliott-with-the-longest-name-on-github]

Want to become a contributor? Open a PR and add a test 😉 If you don't get to it, I'll take a stab at it tomorrow.

[Rican7]

On it!

[Rican7]

PR up: #15083