Typescript: MessageEventSource.postMessage has no compatible call signatures

[marcomura]

TypeScript Version: 3.0.0

Build:Cannot invoke an expression whose type lacks a call signature. Type '((message: any, targetOrigin: string, transfer?: any[]) => void) | ((message: any, transfer?: any...' has no compatible call signatures.

[mattmccutchen]

Looks intentional to me. Before you can post a message to a MessageEventSource, you need to know whether it is a Window (which requires a targetOrigin parameter) or a MessagePort or ServiceWorker (which does not accept a targetOrigin parameter).

[RyanCavanaugh]

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[marcomura]

What else do you need? A repro? The message has all the information you need

[lepture]

@marcomura it seems that you need to detect the event.source before using it. The event.source is type of MessageEventSource, while:

type MessageEventSource = WindowProxy | MessagePort | ServiceWorker;
// and
type WindowProxy = Window;

The solution could be:

if (event.source instanceof Window) {
  event.source.postMessage('message', 'origin')
}

[neekey]

@lepture event.source instanceof Window will return false for me. You should probably use:

!(e.source instanceof MessagePort) && !(e.source instanceof ServiceWorker)

[yuyang545262477]

another resolve:
(<Window>event.source).postMessage('message', 'origin')