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SpeechSynthesisEvent: elapsedTime property

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 elapsedTime read-only property of the SpeechSynthesisEvent returns the elapsed time in seconds, after the SpeechSynthesisUtterance.text started being spoken, at which the event was triggered.

A float containing the elapsed time, in seconds.

Note: Early versions of the specification required the elapsed time in milliseconds. Check the compatibility table below for your browser.

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

Specification
Web Speech API> # dom-speechsynthesisevent-elapsedtime>