SpeechSynthesisUtterance detect onend when only speaking completes once not on cancel

Question

I am using window.SpeechSynthesisUtterance API and I found out when you call window.speechSynthesis.cancel() it immediately also calls onend event. I want to do something specific only when the speaking ends but not when the utterance is canceled while it is being spoken.

How do I detect if speaking ended due to a cancel method call?

The onend event gives and event object:
onend = event => { }

But in both cases when the speech ends or is canceled the event.type is 'end'.