The MediaKeyMessageEvent.message read-only property returns an ArrayBuffer with a message from the content decryption module. Messages vary by key system.

API EncryptedMediaExtensions Experimental MediaKeyMessageEvent message Property Reference

The port1 read-only property of the MessageChannel interface returns the first port of the message channel, the port attached to the context that originated the channel.

API Channel messaging HTML5 Message Channel API MessageChannel Property Reference

The message read-only property of the SpeechRecognitionError interface returns a message describing the error in more detail.

API Experimental message Property recognition Reference speech SpeechRecognitionError Web Speech API