"postMessage" declartion in 'lib.dom.d.ts' may have a little problem

[asurance]

TypeScript Version: 3.3.3

• postMessage declartion in lib.dom.d.ts is

declare function postMessage(message: any, targetOrigin: string, transfer?: Transferable[]): void;

Its second parameter targetOrigin is set as a must.
But I found samples on MDN about postMessage don't pass it.
There may lack a ? after targetOrigin.
When I set use strict of comile options true and don't pass targetOrigin, compiler will warn me ,which makes me X﹏X.

[AviVahl]

Indeed optional according to the living "whatwg" specs.

https://html.spec.whatwg.org/multipage/web-messaging.html#posting-messages

"A target origin can be specified using the targetOrigin member of options. If not provided, it defaults to "/". This default restricts the message to same-origin targets only."

The fix probably needs to come from https://github.com/Microsoft/TSJS-lib-generator

[asurance]

OK,Thank you.

[AviVahl]

The relevant location, I think, is:
https://github.com/Microsoft/TSJS-lib-generator/blob/master/inputfiles/overridingTypes.json#L474

or, if master changes and the line isn't relevant, open overridingTypes.json and search for postMessage.

[sandersn]

Actually, as @saschanaz points out, https://html.spec.whatwg.org/multipage/window-object.html#the-window-object:dom-window-postmessage shows that the parameter targetOrigin is required. When you provide an options object instead, the options object has an optional property named targetOrigin.

[AviVahl]

@saschanaz @sandersn could you please check it out again? The docs you linked to say:

  void postMessage(any message, USVString targetOrigin, optional sequence<object> transfer = []);
  void postMessage(any message, optional WindowPostMessageOptions options);

which means postMessage([anything]) is a valid call. Perhaps the real issue is the types missing the overloaded signature (that has the optional options object).

[sandersn]

@AviVahl I think @saschanaz fixed this in microsoft/TypeScript-DOM-lib-generator#679. Mind taking a look to see if that's the case?

[AviVahl]

@sandersn issue does seem to be fixed in @saschanaz's PR.
you guys are awesome.

[sandersn]

All thanks go to @saschanaz ! I am just a newbie in this space.