ctrlKey属性用于显示在触发键事件时是否按下了CTRL键。您可以尝试运行以下代码，以了解如何在JavaScript中实现ctrlKey属性-
<!DOCTYPE html>
<html>
<body>
<input type = "text" onkeydown = "funcCtrlKey(event)">
<div id = "res">Press any key</div>
<script>
function funcCtrlKey(event) {
var val = document.getElementById("res");
if (event.ctrlKey) {
val.innerHTML = "CTRL key: Pressed";
} else {
val.innerHTML = "CTRL key: NOT Pressed";
}
}
</script>
</body>
</html>