https://developer.mozilla.org/en-US/docs/Web/API/MessageEvent/origin
MessageEvent: origin property - Web APIs | MDN
The origin read-only property of the MessageEvent interface is a string representing the origin of the message emitter.
web apismessageeventoriginpropertymdn
https://api.dart.dev/stable/3.10.8/dart-html/MessageEvent-class.html
MessageEvent class - dart:html library - Dart API
API docs for the MessageEvent class from the dart:html library, for the Dart programming language.
messageeventclassdarthtmllibrary
https://developer.mozilla.org/en-US/docs/Web/API/MessageEvent/data
MessageEvent: data property - Web APIs | MDN
The data read-only property of the MessageEvent interface represents the data sent by the message emitter.
web apismessageeventdatapropertymdn
https://api.dart.dev/stable/3.11.0/dart-html/MessageEvent/data.html
data property - MessageEvent class - dart:html library - Dart API
API docs for the data property from the MessageEvent class, for the Dart programming language.
datapropertymessageeventclassdart