释放键时会触发onkeyup事件。
您可以尝试运行以下代码以了解如何在JavaScript中使用onkeyup事件-
<html>
<head>
<script>
<!--
function sayHello() {
var str = document.getElementById("subject");
str.value = str.value.toLowerCase();
}
//-->
</script>
</head>
<body>
<p>Enter subject below in upper case and see what happpens.</p>
<input type = "text" onkeyup = "sayHello()" id = "subject">
</body>
</html>