webidl-decorators - TypeScript decorators for WebIDL interfaces

A set of TypeScript decorators that let you declare WebIDL interfaces, attributes, and special operations directly on classes. The runtime semantics — platform object behavior, indexed/named property access, setters, and deleters — are provided by @t15i/webspecs.

Coverage is intentionally narrow — this is a knowledge base, not a polyfill. Only the decorators that have been ported so far are listed below; everything else is marked with ....

Install

npm install @t15i/webidl-decorators

Usage

All decorators are exposed from a single entry point:

import {
  Interface,
  Attribute,
  IndexedPropertyGetter,
  NamedPropertyGetter,
  // ...
} from "@t15i/webidl-decorators";

Decorate a class with @Interface and any of its members with the appropriate decorators. Once instantiated, the class behaves as a WebIDL platform object:

import { Interface, Attribute, IndexedPropertyGetter } from "@t15i/webidl-decorators";
import { Nullable, Type, UnsignedLong } from "@t15i/webspecs/webidl";

@Interface
class HTMLCollection {
  @Attribute(UnsignedLong)
  get length(): number {
    // ...
  }

  @IndexedPropertyGetter(Nullable(Type(Element)))
  item(index: number): Element | null {
    // ...
  }
}

The decorator proposal used is the TC39 stage-3 / 2023-11 variant. Make sure your toolchain supports it.

What's implemented

Expand a section to see what is currently ported. ... marks sections with un-ported content.

• §2 Interface definition language
  • §2.2 Interfaces
    • [x] @Interface
  • §2.5 Members
    • §2.5.2 Attributes
      • [x] @Attribute
    • §2.5.6 Special operations
      • §2.5.6.1 Indexed properties
        • [x] @IndexedPropertyGetter
        • [x] @IndexedPropertySetter
        • [x] @IndexedPropertyDeterminator
        • [x] @NewIndexedPropertySetter
        • [x] @ExistingIndexedPropertySetter
        • [x] @SupportedPropertyIndices
      • §2.5.6.2 Named properties
        • [x] @NamedPropertyGetter
        • [x] @NamedPropertySetter
        • [x] @NamedPropertyDeleter
        • [x] @NamedPropertyDeterminator
        • [x] @NewNamedPropertySetter
        • [x] @ExistingNamedPropertySetter
        • [x] @ExistingNamedPropertyDeleter
        • [x] @SupportedPropertyNames
      • ...
    • ...
  • ...
• §3 ECMAScript binding
  • §3.4 Legacy extended attributes
    • §3.4.9 [LegacyUnenumerableNamedProperties]
      • [x] @LegacyUnenumerableNamedProperties
    • ...
  • ...
• ...

License

MIT