/Web APIs

SpeechSynthesisEvent: SpeechSynthesisEvent() constructor

The SpeechSynthesisEvent() constructor creates a new SpeechSynthesisEvent object.

Note: A web developer doesn't typically need to call this constructor, as the browser creates these objects itself when firing events.


new SpeechSynthesisEvent(type, options)



A string with the name of the event. It is case-sensitive and browsers set it to start, end, error, pause, resume, mark, or boundary.


An object that, in addition to the properties defined in Event(), has the following properties:


A SpeechSynthesisUtterance object, which is the speech request the event was triggered on.

charIndex Optional

The index position of the character in SpeechSynthesisUtterance.text that was being spoken when the event was triggered. Its default value is 0.

charLength Optional

The number of characters left to be spoken after the character at the charIndex position. Its default value is 0.

elapsedTime Optional

The elapsed time in seconds, after the SpeechSynthesisUtterance.text started being spoken, at which the event was triggered. Its default value is 0.

name Optional

The name associated with certain types of events: 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. It defaults to the empty string ("").

Return value

A new SpeechSynthesisEvent object.


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
SpeechSynthesisEvent 71 14 49 No 58 16 No 71 62 No 16 10.0

See also

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