SpeechSynthesisUtterance.js

function speak(textToSpeech) {
    var synUtterance = new SpeechSynthesisUtterance(textToSpeech);
    if (voiceSelect.value) {
        synUtterance.voice = speechSynthesis.getVoices().filter(function (voice) { return voice.name == voiceSelect.value; })[0];
    }
    synUtterance.lang = langSelect.value;
    synUtterance.volume = parseFloat(volumeRange.value);
    synUtterance.rate = parseFloat(rateRange.value);
    synUtterance.pitch = parseFloat(pitchRange.value);

    const eventList = ["start", "end", "mark", "pause", "resume", "error", "boundary"];
    eventList.forEach((event) => {
        synUtterance.addEventListener(event, (speechSynthesisEvent) => {
            log(`Fired '${speechSynthesisEvent.type}' event at time '${speechSynthesisEvent.elapsedTime}' and character '${speechSynthesisEvent.charIndex}'.`);
        });
    });
    window.speechSynthesis.speak(synUtterance);
}