delete element.dataset.keyname throws TypeError: 'deleteProperty' on proxy

[WebMechanic]

Describe the bug

To remove an attribute from an element's dataset, you should be able to use the delete operator: delete element.dataset.keyname whether .keyname exists or not.

If .keyname does not already exist on the dataset, the statement throws with a
TypeError: 'deleteProperty' on proxy: trap returned falsish for property 'keyname'.

Native DOM allows to do so and even returns true.

To Reproduce
inside a Browser with native DOM

const elt = document.body;
delete elt.dataset.fubar;  // true

inside a unit test with Happy DOM

const elt = document.body;
delete elt.dataset.fubar;     // throws
delete elt.dataset['fubar'];  // throws too

same but keys are initialised first with "anything"

const elt = document.body;
elt.dataset.foo = null;
delete elt.dataset.foo;  // works

elt.dataset.bar = undefined;
delete elt.dataset.bar;  // works too

Expected behavior
To not throw a TypeError when attempting to delete a non-existing dataset key, but silently ignore that the key does not exist.

Additional context

• Node 16.18.0
• Happy DOM 7.6.6
• Vite 3.2.3
• Vitest vitest/0.24.5

I'm writing a utility to manage multiple values inside data attributes (data-fubar="foo bar bat baz") similar to classList . Between tests I wanted to clean dataset and ran into this issue.
Not a showstopper 'cos I can just used a different key for each suite.

[takaya1992]

delete operator ( deleteProperty ) is always returns true, except under exceptional conditions.

true for all cases except when the property is an own non-configurable property, in which case false is returned in non-strict mode.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/delete#return_value

but, this code returns false when the property not exist, so there is a difference in behavior.

happy-dom/packages/happy-dom/src/nodes/html-element/HTMLElement.ts

Lines 252 to 258 in 67d95f0

	deleteProperty: (dataset: { [key: string]: string }, key: string) => {
	const name = 'data-' + DatasetUtility.camelCaseToKebab(key);
	const exists = !!attributes[name];
	delete attributes[name];
	delete dataset[key];
	return exists;
	},

[btea]

@capricorn86 This issue has been fixed and should be able to be closed.

[sasha-evidation]

@btea This appears to not be fixed as of the latest version (10.11.2). Here's a very simple case that I can reproduce in a Jest test (using the Happy DOM Jest environment):

test("is able to delete a non-existent dataset key", () => {
  delete document.documentElement.dataset.xyz
})

Fails with:

TypeError: 'deleteProperty' on proxy: trap returned falsish for property 'xyz'

[capricorn86]

Thank you for reporting @WebMechanic, @takaya1992, @btea and @sasha-evidation! 🙂

Big thanks to @RussianCow for the contribution ⭐

There is a fix out now:
https://github.com/capricorn86/happy-dom/releases/tag/v12.1.7