代码示例:(标识:event_wheel_deltamode)
<!DOCTYPE html>
<html>
<body onwheel="myFunction(event)">

<h1>WheelEvent deltaMode 属性</h1>

<p>滚动此页面可查看 delta values 属性的长度单位。</p>

<p><b>注释:</b> 0 = 像素, 1 = 线, 2 = 页。</p>

<p id="demo"></p>

<script>
function myFunction(event) {
  var x = event.deltaMode;
  document.getElementById("demo").innerHTML = x;
}
</script>

</body>
</html>
运行结果: