Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since September 2018.

The SpeechSynthesisEvent interface of the Web Speech API contains information about the current state of SpeechSynthesisUtterance objects that have been processed in the speech service.

Event SpeechSynthesisEvent



Creates a new SpeechSynthesisEvent.

Instance properties

The SpeechSynthesisEvent interface also inherits properties from its parent interface, Event.

SpeechSynthesisEvent.charIndex Read only

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

SpeechSynthesisEvent.charLength Read only

Returns the number of characters left to be spoken after the charIndex position, if the speaking engine supports it. Returns 0 if the speaking engine can't provide the information.

SpeechSynthesisEvent.elapsedTime Read only

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

SpeechSynthesisEvent.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.

SpeechSynthesisEvent.utterance Read only

Returns the SpeechSynthesisUtterance instance that the event was triggered on.

Instance methods

The SpeechSynthesisEvent interface also inherits methods from its parent interface, Event.


utterThis.onpause = (event) => {
  const char = event.utterance.text.charAt(event.charIndex);
    `Speech paused at character ${event.charIndex} of "${event.utterance.text}", which is "${char}".`,

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


Web Speech API
# speechsynthesisevent

Browser compatibility

BCD tables only load in the browser

See also