firefox与IE透明度(opacity)设置区别

IE：
filter:alpha(opacity=sqlN)
其中 sqlN的值域为[0, 100]

js: ieNode.style.filter="alpha(opacity=sqlN)";

Firefox,Chrome和Safari：
opacity:sqlN
其中sqlN的值域为[0, 1]

js: firefoxNode.style.opacity=sqlN;

测试代码如下：

<HTML>
<HEAD>
    <style type="text/css">
        .ieCss {
            display:-moz-inline-box;
            display:inline-block;
            width:100;
            height:100;
            background-color:red;
            filter:alpha(opacity=20);
        }
        .fireFoxCss {
            display:-moz-inline-box;
            display:inline-block;
            width:100;
            height:100;
            background-color:blue;
            opacity:0.5;
        }
    </style>

    <script>
        window.onload = function() {
            //设置IE
            var ieSpanJs = document.getElementById("ieSpanJs");
            ieSpanJs.style.display = "inline-block";  //ie支持
            ieSpanJs.style.width = 100;
            ieSpanJs.style.height = 100;
            ieSpanJs.style.backgroundColor = "red";
            ieSpanJs.style.filter="alpha(opacity=20)";

            //设置firefox
            var firefoxSpanJs = document.getElementById("firefoxSpanJs");
            try
            {
                firefoxSpanJs.style.display = "-moz-inline-box"; //firefox支持
            }
            catch (e)
            {
                firefoxSpanJs.style.display = "inline-block"; //支持IE
            }

            firefoxSpanJs.style.width = 100;
            firefoxSpanJs.style.height = 100;
            firefoxSpanJs.style.backgroundColor = "blue";
            firefoxSpanJs.style.opacity="0.5";

        }
    </script>

</HEAD>

<BODY>
<span id="ieSpanCss" class="ieCss">IE_css</span>
<span id="firefoxSpanCss" class="fireFoxCss">firefox_css</span>
<br>
<br>
<span id="ieSpanJs">IE_Js</span>
<span id="firefoxSpanJs">firefox_Js</span>
</BODY>
</HTML>

补充：参考资料中对firfox还有3.5之前和3.5之后版本的区分，暂时忽略。

参考文档：

http://hi.baidu.com/hanserv/item/ac31a23f0c578bffdf222114