测试代码如下：
<!DOCTYPE HTML>
<html lang="zh-cn">
<head>
<meta charset="utf-8" />
<title>Javascript</title>
<style>
body{margin:0;padding:0;background:#ccc;font-size:12px;overflow:auto}
.main{width: 500px;height: 330px;position: relative;margin: 250px auto 0;background-color: #eee;}
.box{position: absolute;width: 220px;height: 180px;background-color: orange;top: 80px;left: 80px;}
</style>
</head>
<body style="height:1600px;">
<div class="main">
<div class="box" id="box"></div>
</div>
<script>
var oBox = document.getElementById('box');
window.onload = function(){
oBox.onmousedown = function(ev){
ev = ev || window.event;
console.log(ev.offsetX, ev.offsetY);
console.log(ev.clientX, ev.clientY);
console.log(ev.pageX, ev.pageY);
console.log(ev.screenX, ev.screenY);
console.log(ev.layerX, ev.layerY);
console.log(ev.x, ev.y);
}
}
</script>
</body>
</html>
二、不同浏览器对这些属性的支持：
三、图解 event.offsetX，event.clientX，event.pageX，event.screenX属性
四、图解 event.layerX，event.layerY 属性
五、图解 event.x，event.y 属性
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
六、Jquery 兼容写法
Jquery event 事件对象，包含有 event.offsetX， event.clientX，event.pageX，event.screenX等属性（firefox 浏览器中， offsetX 为 undefined）。firefox 获取 offsetX / offsetY 的值，需要通过 event 对象的属性 originalEvent。
<script>
$(function(){
$("#box").mousedown(function(event){
console.log(event.offsetX, event.offsetY);
console.log(event.clientX, event.clientY);
console.log(event.pageX, event.pageY);
console.log(event.screenX, event.screenY);
/* firefox */
console.log(event.originalEvent.layerX, event.originalEvent.layerY);
});
});
</script>
