Some interfaces and properties declared in lib.dom are not being used by TS 3.9.2

[Serabe]

TypeScript Version: 3.9.2

Search Terms: "types not found 3.9", "TS2304", "TS4060"

Code

function getTracks(media: HTMLMediaElement): AudioTrackList {
    return media.audioTracks;
}

Expected behavior: AudioTrackList and property audioTracks are recognised as they were in 3.8.3

Actual behavior: Several errors of type TS2304 and TS4060 are being raised.

Playground Link:

• Playground TS 3.8.3 (no error)
• Playground TS 3.9.2 (error)

Related Issues: No

[ShuiRuTian]

This change is done in microsoft/TypeScript-DOM-lib-generator#802
But it seems reasonable and might not be a bug:
DefinitelyTyped/DefinitelyTyped#43270
DefinitelyTyped/DefinitelyTyped#43335
DefinitelyTyped/DefinitelyTyped#43362

[Serabe]

HTMLMediaElement.audioTracks Supported in Firefox >=33 (behind feature flag), Opera and Safari.
AudioTrackList Supported on Chrome >= 45(behind feature flag), Edge >=12, Firefox >=33 (behind feature flag), Internet Explorer >= 10, Safari.

How can it be argued that it is not standard when it is in the HTML Living spec as of today (last update was on May, 13th)?

[ShuiRuTian]

Make sense to me. So what we could do is just leave it to typescript team, for we do not exactly know the final decision?
Would it be better to remove "help wanted" label?

[orta]

Hi folks, we document the heuristics which we use to determine if something is production ready for being added to our dom APIs.

Being only available on just IE and Safari isn't stable enough for inclusion yet (maybe that'll change by the time 4.0 rolls around and it can be added back

You can add an ambient *.d.ts to your project with:

interface AudioTrackList {
     [Symbol.iterator](): IterableIterator<AudioTrack>;
 }

interface HTMLVideoElement {
  readonly audioTracks: AudioTrackList

  msFrameStep(forward: boolean): void;
  msInsertVideoEffect(activatableClassId: string, effectRequired: boolean, config?: any): void;
  msSetVideoRectangle(left: number, top: number, right: number, bottom: number): void;
  webkitEnterFullScreen(): void;
  webkitEnterFullscreen(): void;
  webkitExitFullScreen(): void;
  webkitExitFullscreen(): void;

  msHorizontalMirror: boolean;
  readonly msIsLayoutOptimalForPlayback: boolean;
  readonly msIsStereo3D: boolean;
  msStereo3DPackingMode: string;
  msStereo3DRenderMode: string;
  msZoom: boolean;
  onMSVideoFormatChanged: ((this: HTMLVideoElement, ev: Event) => any) | null;
  onMSVideoFrameStepCompleted: ((this: HTMLVideoElement, ev: Event) => any) | null;
  onMSVideoOptimalLayoutChanged: ((this: HTMLVideoElement, ev: Event) => any) | null;
  webkitDisplayingFullscreen: boolean;
  webkitSupportsFullscreen: boolean;
}

interface MediaError {
  readonly msExtendedCode: number;
  readonly MS_MEDIA_ERR_ENCRYPTED: number;
}

To bring them back until it's is further down the standard process 👍

[typescript-bot]

This issue has been marked as 'Question' and has seen no recent activity. It has been automatically closed for house-keeping purposes. If you're still waiting on a response, questions are usually better suited to stackoverflow.

[robwalch]

You can add an ambient *.d.ts to your project with:

Tried this with typescript @4.1.4 but then I get error TS2304: Cannot find name 'AudioTrack'.. So what happened to the definition of AudioTrack?

Not only that, but TS2339: Property 'length' does not exist on type 'AudioTrackList'. :(