onkeypress事件在按下和释放键时触发。您可以尝试运行以下代码以了解如何在JavaScript中使用onkeypress事件-
<html>
<head>
<script>
<!--
function sayHello() {
alert("A key is pressed.")
}
//-->
</script>
</head>
<body>
<input type = "text" onkeypress = "sayHello()">
</body>
</html>