当前，我的背景视频只会在用户在警报弹出窗口中按"好"之后播放。如何创建代码以在窗口出现或页面加载后立即进行背景视频播放，而不必从警报中按OK。背景视频需要在警报出现之前进行播放。我是JavaScript的新手，因此我需要代码示例或对当前代码进行编辑才能正确理解。
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Untitled Document</title>
</head>
<body>
<script>
function myText() {
var txt;
var person = prompt("What's your name?", "");
if (person == null || person == "") {
txt = "User cancelled the prompt.";
} else {
txt = "Hello " + person + "! How are you today?";
}
document.getElementById("demo").innerHTML = txt;
}
function playAlert(msg, wav) {
return new Promise(function(resolve) {
var audio = new Audio(wav);
audio.addEventListener('canplay', function(e) {
audio.play();
alert(msg);
resolve();
});
});
}
window.onload = function() {
document.getElementById("video");
};
playAlert("Thank you.", 'Images/thankyou.wav?.wav?.wav?.wav?.wav')
.then(function() {
return playAlert("Sorry, I haven't introduced myself.", 'Images/sorry.wav?.wav?.wav');
})
.then(function() {
return myText("My name is Eve. What is your name?", 'Images/mynameiseve.wav?.wav?.wav');
})
.then(function() {
return playAlert("Can you hear me?", 'Images/canyouhearme.wav?.wav');
});
</script>
<video controls id="video" width="1300px" height="auto" preload="auto" autoplay="autoplay">
<source src="images/thirdeve.mp4" type="video/mp4"/>
</video>
</body>
</html>
如果您的JavaScript调用警报，则警报将是第一件事。在清除警报之前，什么都不会发生。