RTCDataChannel.send fails to compile

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Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
50/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
typescript
Domain
tooling, web-dev

Research direction

Start by locating the generator input or declaration source for RTCDataChannel.send, then compare it with the WebRTC and MDN references linked in the issue. Verify that the generated lib.dom.d.ts accepts the ArrayBufferView | string example without narrowing and that the resulting overload declaration matches the documented API.

Written by the indexing model from the issue text.

Description

Code that should compile but doesn't

function sendIt (peerConnection: RTCPeerConnection, data: ArrayBufferView | string): void {
  const dc = peerConnection.createDataChannel('')
  dc.send(data)
}

Reason

RTCDataChannel.send accepts string | Blob | ArrayBuffer | ArrayBufferView but because the .send method is declared as multiple overrides you have to work out the type of the argument before you invoke the method, even though you don't actually do anything to the data before sending:

// lib.dom.d.ts line 18,000
/** [MDN Reference](https://developer.mozilla.org/docs/Web/API/RTCDataChannel/send) */
send(data: string): void;
send(data: Blob): void;
send(data: ArrayBuffer): void;
send(data: ArrayBufferView): void;

function sendIt (peerConnection: RTCPeerConnection, data: ArrayBufferView | string): void {
  const dc = peerConnection.createDataChannel('')

  if (typeof data === 'string') {
    dc.send(data)
  } else {
    dc.send(data)
  }
}

Changing it to the following works:

/** [MDN Reference](https://developer.mozilla.org/docs/Web/API/RTCDataChannel/send) */
send(data: string | Blob | ArrayBuffer | ArrayBufferView) void;

Reference

Dominant language
TypeScript
Stars
740
Forks
474
Avg merge
2d 8h
Merged PRs (30d)
15

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