Work in progress: Record & Tuple integration

[rricard]

• At least two implementers are interested (and none opposed):
  • …
  • …
• Tests are written and can be reviewed and commented upon at:
  • …
• Implementation bugs are filed:
  • Chrome: …
  • Firefox: …
  • Safari: …
  • Deno: …
  • Node.js: …
  • webidl2.js: …
  • widlparser: …

(See WHATWG Working Mode: Changes for more details.)

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This candidate change aims to integrate the now Stage 2 Record & Tuple TC39 proposal in WebIDL.

Our current & minimal goal in integrating in WebIDL is to first make APIs tolerate Records in-place of option bags and Tuples in-place of enumerables. This means we are only defining an interaction with ECMAScript for now, no new WebIDL types. This would enable a developer to write the following:

const headers = #{
  'Content-Type': 'text/xml',
};
await fetch('https://example.com/', #{ method: "PUT", headers });

If and when Record & Tuple usage in JS is proven and DOM APIs would want to be able to return them, we will consider adding them as WebIDL types.