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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

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
boundary_event
33The boundary event does not fire as expected. See bug 1122143.
14 49 No 21 7 No
33The boundary event does not fire as expected. See bug 1122143.
62 No 7 3.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/SpeechSynthesisUtterance/boundary_event