MouseEvent.offsetX
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
MouseEvent 接口的只读属性 offsetX 规定了事件对象与目标节点的内填充边（padding edge）在 X 轴方向上的偏移量。
语法
var xOffset = instanceOfMouseEvent.offsetX;
返回值
一个双精度 浮点值。早期的规范将其规定为整数值。详见浏览器兼容性部分。
规范
| Specification |
|---|
| CSSOM View Module # dom-mouseevent-offsetx |
浏览器兼容性
BCD tables only load in the browser