JavaScript speech synthesis cheatsheet

SpeechSynthesisUtterance

function speak (message) {
  var msg = new SpeechSynthesisUtterance(message)
  var voices = window.speechSynthesis.getVoices()
  msg.voice = voices[0]
  window.speechSynthesis.speak(msg)
}

speak('Hello, world')

See: SpeechSynthesisUtterance (developer.mozilla.org)