The onerror property of the SpeechSynthesisUtterance interface represents an event handler that will run when an error occurs that prevents the utterance from being succesfully spoken (when the error event fires.)
The onboundary property of the SpeechSynthesisUtterance interface represents an event handler that will run when the spoken utterance reaches a word or sentence boundary (when the boundary event fires.)
The onend property of the SpeechSynthesisUtterance interface represents an event handler that will run when the utterance has finished being spoken (when the end event fires.)
The onmark property of the SpeechSynthesisUtterance interface represents an event handler that will run when the spoken utterance reaches a named SSML mark tag (when the mark event fires.)
The onpause property of the SpeechSynthesisUtterance interface represents an event handler that will run when the utterance is paused part way through (when the pause event fires.)
The onresume property of the SpeechSynthesisUtterance interface represents an event handler that will run when a paused utterance is resumed (when the resume event fires.)
The onstart property of the SpeechSynthesisUtterance interface represents an event handler that will run when the utterance has begun to be spoken (when the start event fires.)