<input> value and other properties should accept more types

[justinfagnani]

Right now a binding like:

html`<input type="range" .value=${currentValue} .max=${max}>`;

Will report errors on the value and max bindings if currentValue and max are numbers. But an input handles this just fine. This may be something that needs to be updated in the typings, but maybe there's something to be done in the plugin?

[runem]

Thanks for your issue! This plugin uses properties and types from lib.dom.d.ts. Here are some of the properties on HTMLInputElement:

interface HTMLInputElement extends HTMLElement {

    ...

    value: string
    max: string;
    maxLength: number;
    min: string;
    minLength: number;

    ...
}

Typescript TSJSlib-generator seems to be generating these files based on IDL. For example max on HTMLInputElement is attribute DOMString max and maxLength is attribute long maxLength.

I'm already patching some of these types but I have problems finding an overview of properties accepting other types than described in the IDL. Do you know if there exists a clear overview, or if it's safe to assume that eg. all properties of type string also accepts number?

If not I plan on patching the type of each built in property manually when I get the time :-)

[justinfagnani]

This actually might be a good question to bring up to @DanielRosenwasser and the TypeScript team. Since so many DOM setters perform type coercion, and so accept any number of types, what should their real types be?

input.value = 5;

is perfectly fine JavaScript...

[DanielRosenwasser]

I think this ties back into having separate read types and write types, which I'm personally not opposed to if we can think it through. Putting together a short issue that we can track might be helpful if one doesn't already exist.

[justinfagnani]

@DanielRosenwasser did you ever put together a tracker issue for this?

[justinfagnani]

I filed an upstream issue for this.

[graynorton]

Looks like the underlying TypeScript support is in place as of v4.3: microsoft/TypeScript#42425