The start event of the Web Speech API SpeechRecognition object is fired when the speech recognition service has begun listening to incoming audio with intent to recognize grammars associated with the current SpeechRecognition.

Use the event name in methods like addEventListener(), or set an event handler property.

addEventListener("start", (event) => {});

onstart = (event) => {};

A generic Event with no added properties.

You can use the start event in an addEventListener method:

const recognition = new webkitSpeechRecognition() || new SpeechRecognition();

recognition.addEventListener("start", () => {
  console.log("Speech recognition service has started");
});

Or use the onstart event handler property:

recognition.onstart = () => {
  console.log("Speech recognition service has started");
};

• Web Speech API