SpeechSynthesisUtterance: start event

The start event of the Web Speech API SpeechSynthesisUtterance object is fired when the utterance has begun to be spoken.


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

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

onstart = (event) => {};

Event type

Event properties

In addition to the properties listed below, properties from the parent interface, Event, are available.

charIndex Read only

Returns the index position of the character in the SpeechSynthesisUtterance.text that was being spoken when the event was triggered.

elapsedTime Read only

Returns the elapsed time in seconds after the SpeechSynthesisUtterance.text started being spoken that the event was triggered at.

name Read only

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.

utterance Read only

Returns the SpeechSynthesisUtterance instance that the event was triggered on.


You can use the start event in an addEventListener method:

utterThis.addEventListener("start", (event) => {
  console.log(`We have started uttering this speech: ${event.utterance.text}`);

Or use the onstart event handler property:

utterThis.onstart = (event) => {
  console.log(`We have started uttering this speech: ${event.utterance.text}`);


Web Speech API
# eventdef-speechsynthesisutterance-start
Web Speech API
# dom-speechsynthesisutterance-onstart

Browser compatibility

BCD tables only load in the browser

See also