SpeechSynthesis
The SpeechSynthesis
interface of the Web Speech API is the controller interface for the speech service; this can be used to retrieve information about the synthesis voices available on the device, start and pause speech, and other commands besides.
Instance properties
SpeechSynthesis
also inherits properties from its parent interface, EventTarget
.
SpeechSynthesis.paused
Read only-
A boolean value that returns
true
if theSpeechSynthesis
object is in a paused state. SpeechSynthesis.pending
Read only-
A boolean value that returns
true
if the utterance queue contains as-yet-unspoken utterances. SpeechSynthesis.speaking
Read only-
A boolean value that returns
true
if an utterance is currently in the process of being spoken — even ifSpeechSynthesis
is in a paused state.
Instance methods
SpeechSynthesis
also inherits methods from its parent interface, EventTarget
.
SpeechSynthesis.cancel()
-
Removes all utterances from the utterance queue.
SpeechSynthesis.getVoices()
-
Returns a list of
SpeechSynthesisVoice
objects representing all the available voices on the current device. SpeechSynthesis.pause()
-
Puts the
SpeechSynthesis
object into a paused state. SpeechSynthesis.resume()
-
Puts the
SpeechSynthesis
object into a non-paused state: resumes it if it was already paused. SpeechSynthesis.speak()
-
Adds an
utterance
to the utterance queue; it will be spoken when any other utterances queued before it have been spoken.
Events
Listen to this event using addEventListener()
or by assigning an event listener to the oneventname
property of this interface.
voiceschanged
-
Fired when the list of
SpeechSynthesisVoice
objects that would be returned by theSpeechSynthesis.getVoices()
method has changed. Also available via theonvoiceschanged
property.
Examples
First, a simple example:
js
let utterance = new SpeechSynthesisUtterance("Hello world!");
speechSynthesis.speak(utterance);
Now we'll look at a more fully-fledged example. In our Speech synthesizer demo, we first grab a reference to the SpeechSynthesis controller using window.speechSynthesis
. After defining some necessary variables, we retrieve a list of the voices available using SpeechSynthesis.getVoices()
and populate a select menu with them so the user can choose what voice they want.
Inside the inputForm.onsubmit
handler, we stop the form submitting with preventDefault(), create a new SpeechSynthesisUtterance
instance containing the text from the text <input>
, set the utterance's voice to the voice selected in the <select>
element, and start the utterance speaking via the SpeechSynthesis.speak()
method.
js
const synth = window.speechSynthesis;
const inputForm = document.querySelector("form");
const inputTxt = document.querySelector(".txt");
const voiceSelect = document.querySelector("select");
const pitch = document.querySelector("#pitch");
const pitchValue = document.querySelector(".pitch-value");
const rate = document.querySelector("#rate");
const rateValue = document.querySelector(".rate-value");
let voices = [];
function populateVoiceList() {
voices = synth.getVoices();
for (let i = 0; i < voices.length; i++) {
const option = document.createElement("option");
option.textContent = `${voices[i].name} (${voices[i].lang})`;
if (voices[i].default) {
option.textContent += " — DEFAULT";
}
option.setAttribute("data-lang", voices[i].lang);
option.setAttribute("data-name", voices[i].name);
voiceSelect.appendChild(option);
}
}
populateVoiceList();
if (speechSynthesis.onvoiceschanged !== undefined) {
speechSynthesis.onvoiceschanged = populateVoiceList;
}
inputForm.onsubmit = (event) => {
event.preventDefault();
const utterThis = new SpeechSynthesisUtterance(inputTxt.value);
const selectedOption =
voiceSelect.selectedOptions[0].getAttribute("data-name");
for (let i = 0; i < voices.length; i++) {
if (voices[i].name === selectedOption) {
utterThis.voice = voices[i];
}
}
utterThis.pitch = pitch.value;
utterThis.rate = rate.value;
synth.speak(utterThis);
inputTxt.blur();
};
Specifications
Specification |
---|
Web Speech API # tts-section |
Browser compatibility
BCD tables only load in the browser