Add indexing operators for getter and setter attributes

[parlough]

DOMStringMap, primarily returned by HTMLElement#dataset does not provide any mechanism to set or access its values.

Would be nice if it implemented something like Map<String, String> if that was possible :)

See

web/tool/generator/translator.dart

Line 492 in e89fe49

// TODO(joshualitt): We may be able to handle some unnamed

[kevmoo]

I've ran into this, too! CC @srujzs

[srujzs]

I'm surprised we don't emit some properties already:

https://github.com/w3c/webref/blob/8d7678e1740d00c3b79ebf70013d0448b23e3c8b/ed/idl/html.idl#L161

It might be due to us not handling getter and setter? Maybe we should emit them using [] and []=. https://webidl.spec.whatwg.org/#idl-special-operations

That being said, I don't think we can feasibly implement Map (or any Dart collections type), but hopefully the indexing operations are enough!

[adrianlmm]

This one is a show stopper for me, I can't start the migration from 'dart:html' to 'web' until it gets fixed.

[srujzs]

Can you describe a bit more on what's affecting your migration? If it's the above indexing operators, you can define your own external extension members on any interop type if they're not available: https://dart.dev/interop/js-interop/usage#extension-members-on-interop-types e.g.

import 'dart:js_interop';
import 'dart:js_interop_unsafe';

extension on DOMStringMap {
  external String operator [](String name);
  external void operator []=(String name, String value);
  void delete(String name) => this.delete(name.toJS);
}

Matching the definition here: https://html.spec.whatwg.org/multipage/dom.html#embedding-custom-non-visible-data-with-the-data-*-attributes:domstringmap-3.

[kevmoo]

From a grep of the IDL directory, there are a LOT of these!

[rutvik110]

@srujzs I was looking into this issue and was wondering how I can approach this? Would the addition of [] and []= operators on DOMStringMap be sufficient here to address this particular issue or would we also need to add handlers in the bindings generator tool for getter and setter special operations to fully support what this issue describes. If so, how can one approach adding support for them in the generator? Any examples I can look into?

[srujzs]

I think ideally we'll want these in the generator as lots of types define them. The generator has enough layers that it may be a bit complicated to dive into. I'm working on adding this request, but the resulting PR may be useful as an example of how it works and we can chat on that PR.

[rutvik110]

Sounds good!