Describe the problem

The form enhancement that ships in the demo ignores the form[enctype] and always posts the data as a multi-part form using FormData.

While the <form> elements in the todos component do not explicitly define the enctype, they inherit the default value of application/x-www-form-urlencoded.

In other words, the behaviour differs depending on the context:

I think it would be preferable for the JS version to mirror the behaviour of native HTML form. Especially if this ends up becoming core functionality in sveltekit.

Describe the proposed solution

Modify the enhance action so that it mirrors browser behaviour.

According to MDN, enctype can be set on the form itself, but it can also be overridden by a formenctype on the button which triggered the submit. The submit button is accessible on the SubmitEvent

For example:

-        const body = new FormData(form);
+        const formData = new FormData(form);
+        const enctype = event.submitter.formEnctype || form.enctype;
+        const body = (enctype === 'multipart/form-data')
+            ? formData
+            : new URLSearchParams(formData);

Notes

• URLSearchParams is not available in IE

Alternatives considered

Documentation/comments so that developers are not caught off-guard.

Importance

nice to have

Additional Information

No response