一、不同浏览器的鼠标滚轮事件
首先，不同的浏览器有不同的滚轮事件。主要是有两种，onmousewheel（IE/Opera/Chrome支持，firefox不支持）和DOMMouseScroll（只有firefox支持）
另外在操作的过程中需要添加事件监听，兼容性写法
代码如下：
/*注册事件*/
if(document.addEventListener){
document.addEventListener('DOMMouseScroll',scrollFunc,false); // W3C
}
window.onmousewheel=document.onmousewheel=scrollFunc; // IE/Opera/Chrome
二、通过js事件event对象的返回数值判断滚轮上下
判断滚轮向上或向下在浏览器中也要考虑兼容性，现在五大浏览器（IE、Opera、Safari、Firefox、Chrome）中Firefox 使用detail，其余四类使用wheelDelta；
两者只在取值上不一致，代表含义一致，detail与wheelDelta只各取两个值，detail只取±3，wheelDelta只取±120，其中正数表示为向上，负数表示向下。
代码如下：
<label for="wheelDelta">滚动值:</label>(IE/Opera)<input type="text" id="wheelDelta"/>
<label for="detail">滚动值:(Firefox)</label><input type="text" id="detail"/>
<script type="text/javascript">
var scrollFunc = function(e){
e = e || window.event;
var t1 = document.getElementById("wheelDelta");
var t2 = document.getElementById("detail");
if( e.wheelDelta ){ // IE/Opera/Chrome
t1.value = e.wheelDelta;
}else if( e.detail ){ // Firefox
t2.value = e.detail;
}
}
/*注册事件*/
if(document.addEventListener){
document.addEventListener('DOMMouseScroll',scrollFunc,false); // W3C
}
window.onmousewheel=document.onmousewheel=scrollFunc; // IE/Opera/Chrome
</script>
效果如下：
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alt="" />aaarticlea/png;base64,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" alt="" />
通过运行上述代码我们可以看到：
在非firefox浏览器中，滚轮向上滚动返回的数值是120，向下滚动返回-120。
而在firefox浏览器中，滚轮向上滚动返回的数值是-3，向下滚动返回3
代码部分如下，e.wheelDelta是判断是否为非firefox浏览器，e.detail为firefox浏览器
if(e.wheelDelta){ // IE/Opera/Chrome
t1.value=e.wheelDelta;
}else if(e.detail){ // Firefox
t2.value=e.detail;
}