SpeechSynthesisUtterance: boundary event

The boundary event of the Web Speech API is fired when the spoken utterance reaches a word or sentence boundary.

Syntax

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

js
addEventListener("boundary", (event) => {});

onboundary = (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.

Examples

You can use the boundary event in an addEventListener method:

js
utterThis.addEventListener("boundary", (event) => {
  console.log(
    `${event.name} boundary reached after ${event.elapsedTime} seconds.`,
  );
});

Or use the onboundary event handler property:

js
utterThis.onboundary = (event) => {
  console.log(
    `${event.name} boundary reached after ${event.elapsedTime} seconds.`,
  );
};

Specifications

Specification
Web Speech API
# eventdef-speechsynthesisutterance-boundary
Web Speech API
# dom-speechsynthesisutterance-onboundary

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobile
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
boundary event

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support
Partial support
Partial support
No support
No support

See also