Returns the index position of the character in the
SpeechSynthesisUtterance.text that was being spoken when the event was triggered.
Returns the elapsed time in milliseconds after the
SpeechSynthesisUtterance.text started being spoken that the event was triggered at.
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