是否可以使用语音合成API脱机？如果是这样，我可以使用多种语言还是默认语言？我尝试过此代码，并且可以在线工作，但它无法离线工作。我该如何在线工作？
<html>
<head>
<title>Index</title>
</head>
<p id = "1"></p>
<script src="../js/jquery-3.2.1.js"></script>
<script type="text/javascript">
$(document).ready(function() {
document.addEventListener("keydown", function (e) {
var audio = document.getElementById("myAudio");
if (e.keyCode ===49 || e.keyCode ===97) { //1 is pressed
mySpeech();
}
});
})
function mySpeech(){
var msg = new SpeechSynthesisUtterance();
var voices = window.speechSynthesis.getVoices();
msg.voiceURI = 'native';
msg.lang = 'it-IT'
//msg.voice = voices[$('#voices').val()];
msg.rate = 1; // 0 to 1
msg.pitch = 1; // 0 to 2
msg.text = "hello world";
speechSynthesis.speak(msg);
}
</script>
</body>
唯一脱机的语言是浏览器的本地声音。