javascript SpeechSynthesis API onend 回调不起作用
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SpeechSynthesis API onend callback not working
提问by huu
I'm using the Speech Synthesis APIon Google Chrome v34.0.1847.131. The API is implemented in Chrome starting in v33.
我在 Google Chrome v34.0.1847.131 上使用语音合成 API。从 v33 开始，该 API 在 Chrome 中实现。
The text-to-speech works for the most part, except when assigning a callback to onend. For instance, the following code:
文本转语音在大多数情况下都有效，除非将回调分配给onend。例如，以下代码：
var message = window.SpeechSynthesisUtterance("Hello world!");
message.onend = function(event) {
console.log('Finished in ' + event.elapsedTime + ' seconds.');
};
window.speechSynthesis.speak(message);
will sometimes call onendand sometimes not call it. The timing appears to be completely off. When it does get called, the printed elapsedTimeis always some epoch time like 1399237888.
有时会调用onend有时不调用。时间似乎完全关闭。当它被调用时，打印出来elapsedTime的总是像1399237888.
采纳答案by Muhammad Umer
While this is how I found it to make it work, I am not sure if this is the right behavior....
虽然这是我发现它起作用的方式，但我不确定这是否是正确的行为......
First don't call the speak function it right away, use callback.
首先不要马上调用speak函数，使用回调。
2nd, to get time use timeStampinstead of elapsedTime. You could have just used performance.now()as well.
2，获得时间使用timeStamp而不是elapsedTime. 你也可以使用performance.now()。
var btn = document.getElementById('btn');
speechSynthesis.cancel()
var u = new SpeechSynthesisUtterance();
u.text = "This text was changed from the original demo.";
var t;
u.onstart = function (event) {
t = event.timeStamp;
console.log(t);
};
u.onend = function (event) {
t = event.timeStamp - t;
console.log(event.timeStamp);
console.log((t / 1000) + " seconds");
};
btn.onclick = function () {speechSynthesis.speak(u);};
Demo: http://jsfiddle.net/QYw6b/2/
演示：http: //jsfiddle.net/QYw6b/2/
you get time passed and both events fired for sure.
时间过去了，这两个事件肯定会被触发。
回答by techpeace
According to this commenton the bug mentioned in the answerfrom Kevin Hakanson, it might be a problem with garbage collection. Storing the utterance in a variable before calling speakseems to do the trick:
根据对Kevin Hakanson的回答中提到的错误的评论，这可能是垃圾收集的问题。在调用之前将话语存储在变量中似乎可以解决问题：speak
window.utterances = [];
var utterance = new SpeechSynthesisUtterance( 'hello' );
utterances.push( utterance );
speechSynthesis.speak( utterance );
回答by fimbim
You could use the EventListener for start and end like I did for Speakerbot (http://www.speakerbot.de/).
您可以像我为 Speakerbot ( http://www.speakerbot.de/)所做的那样使用 EventListener 开始和结束。
Here my face changes while words are spoken.
在这里，说话时我的脸色会发生变化。
newUtt = new SpeechSynthesisUtterance();
newUtt.addEventListener('start', function () {
console.log('started');
})
newUtt.addEventListener('end', function () {
console.log('stopped');
})
回答by Mapio
I found both solutions suggested here not working in an app I just wrote. The only solution I could come up with is a (sort of) busy waiting:
我发现这里建议的两种解决方案都不适用于我刚刚编写的应用程序。我能想出的唯一解决方案是（有点）忙着等待：
function speak( text, onend ) {
window.speechSynthesis.cancel();
var ssu = new SpeechSynthesisUtterance( text );
window.speechSynthesis.speak( ssu );
function _wait() {
if ( ! window.speechSynthesis.speaking ) {
onend();
return;
}
window.setTimeout( _wait, 200 );
}
_wait();
}
you can find a complete example in this codepen
你可以在这个代码笔中找到一个完整的例子
回答by Kevin Hakanson
回答by yun
print the utterance before speak seems working... If I remove the console, this issue will happen, don't know why
在说话之前打印话语似乎工作......如果我删除控制台，就会发生这个问题，不知道为什么
console.log("utterance", utterThis);
synth.speak(utterThis);
回答by Bruce Allen
I also found the only way to make this work reliably is to use .cance. I use a 17 second timeout. All of my recordings are under 20 seconds so this works for me.
我还发现使这项工作可靠的唯一方法是使用 .cance。我使用 17 秒超时。我所有的录音都不到 20 秒，所以这对我有用。
utterance.onstart = function (event) {
setTimeout(function(){window.speechSynthesis.cancel();},17000);
};
Before I would run into this problem once every 8-10 messages it attempted. Once I added .cancel it seems to always work. I also call set timeout when invoking.
在我每尝试 8-10 条消息就会遇到这个问题之前。一旦我添加了 .cancel 它似乎总是有效。调用时我也调用 set timeout 。
setTimeout(function(){window.speechSynthesis.speak(utterance);},100);
