通过 3 张图和 1 张表格，轻松区别 Javascript Event 对象中的offsetX, clientX, pageX, screenX, layerX, x等属性。
一、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：
点击这里查看大图
点击这里查看大图
点击这里查看大图
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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>