Javascript img 更改语句过早触发

Question

我正在制作 Nest 的烟雾和一氧化碳报警器 Nest Protect 模拟器。但是当我按下按钮（点击）时，内环并没有像预期的那样变成蓝色。它会说话，就像我使用 ResponsiveVoice 一样，但它就是不亮！这是我的（未完成的）代码。

<script src="http://code.responsivevoice.org/responsivevoice.js"></script>    
<script>
function delay(millis)  {
    var date = new Date();
    var curDate = null;
    do { curDate = new Date(); }
    while(curDate-date < millis);
}
function press() {
    document.getElementById("unit").src = "assets/img/blue.jpg";
    delay(500);
    responsiveVoice.speak("Ready. In the Living Room. Press to test.");
    delay(500);
    document.getElementById("unit").src = "assets/img/idle.jpg";


}
</script>

Answer 1

你可以试试这个：

function delay(millis, action)  {
    setTimeout(action, millis);
}

function press () {
    document.getElementById("unit").src = "assets/img/blue.jpg";
    delay(500,
        function () {
            responsiveVoice.speak("Ready. In the Living Room. Press to test.");
        }
    );
    delay(1000,
        function () {
            document.getElementById("unit").src = "assets/img/idle.jpg";
        }
    );
}

最好使用 setTimeout 或 setInterval，因为大多数浏览器对 javascript 使用单线程，您当前的函数会使页面在等待时无响应。这允许您异步执行其他操作。

Javascript img 更改语句过早触发

Javascript img change statement fires too early

javascript

responsivevoice