触发事件后，screenY鼠标事件将返回鼠标指针的垂直坐标。
您可以尝试运行以下代码，以了解如何在JavaScript中实现screenY Mouse事件。
<!DOCTYPE html>
<html>
<body>
<p onclick = "coordsFunc(event)">Click here to get the x (horizontal) and y (vertical) coordinates of the mouse pointer.</p>
<script>
function coordsFunc(event) {
var x_coord = event.screenX;
var y_coord = event.screenY;
var xycoords = "X coords= " + x_coord + ", Y coords= " + y_coord;
document.write(xycoords);
}
</script>
</body>
</html>