The name read-only property of the SpeechSynthesisUtterance interface returns the name associated with certain types of events occurring as the SpeechSynthesisUtterance.text is being spoken: the name of the SSML marker reached in the case of a mark event, or the type of boundary reached in the case of a boundary event.
A string.
utterThis.onboundary = (event) => {
console.log(
`${event.name} boundary reached after ${event.elapsedTime} seconds.`,
);
};