Input with type="file" and two-way binding doesn't track empty fileList

[TGlide]

Describe the bug

If you have an input like so:

<input type="file" bind:files bind:this={input}>

And set files to null or (new DataTransfer()).files, after having chosen a file, input.files still contains the file chosen. The only way to properly reset both files and input.files is setting them both to (new DataTransfer()).files.

Reproduction

https://svelte.dev/repl/c0813e09c2f744e499e86975c9eea13f?version=3.55.1

Logs

No response

System Info

Browsers: Firefox 110.0; Chrome 110.0.5481.177
OS: Window 10
Svelte Version: 3.55.1

Severity

annoyance

[brunnerh]

Note that you cannot reset the selected files with null according to the spec:

On setting, it must run these steps:

• If the IDL attribute does not apply or the given value is null, then return.
• Replace the element's selected files with the given value.

But it looks like the binding is only one-way (read). Related:

• File input binding fails if type declared last #3828

Where Rich Harris stated:

Svelte shouldn't attempt to assign to input.files

It should, though. The spec does not define the attribute as readonly.

[dummdidumm]

Svelte 5 will allow writing to bind:files