如何在IE6下，应用disabled到Select标签的Option上的方法

在开发web程序的时候，我需要将页面下拉框<select>的某个选项<option>给关闭掉，即用户可以看到但是不能选择这个选项，我们可以这样做：

<select>
  <option value="volvo">Volvo</option>
  <option value="saab">Saab</option>
  <option value="mercedes" disabled>Mercedes</option>
  <option value="audi">Audi</option>
</select>

即通过"disabled"可以让选项处于关闭状态，用户不能选择。但是头疼的问题来了，IE7以上版本支持，在IE6下，"disabled"是不起作用的，有一个解决方案Select, Option, Disabled And The JavaScript Solution 是通过javascript模拟关闭状态，效果不错。

select-option-disabled-emulation.js 文件如下：

/****************************************************************
* Author:    Alistair Lattimore
* Website:    http://www.lattimore.id.au/
* Contact:    http://www.lattimore.id.au/contact/
*            Errors, suggestions or comments
* Date:        30 June 2005
* Version:    1.0
* Purpose:    Emulate the disabled attributte for the <option> 
*            element in Internet Explorer.
* Use:        You are free to use this script in non-commercial
*            applications. You are however required to leave
*            this comment at the top of this file.
*
*            I'd love an email if you find a use for it on your 
*            site, though not required.
****************************************************************/

window.onload = function() {
    if (document.getElementsByTagName) {
        var s = document.getElementsByTagName("select");

        if (s.length > 0) {
            window.select_current = new Array();

            for (var i=0, select; select = s[i]; i++) {
                select.onfocus = function(){ window.select_current[this.id] = this.selectedIndex; }
                select.onchange = function(){ restore(this); }
                emulate(select);
            }
        }
    }
}

function restore(e) {
    if (e.options[e.selectedIndex].disabled) {
        e.selectedIndex = window.select_current[e.id];
    }
}

function emulate(e) {
    for (var i=0, option; option = e.options[i]; i++) {
        if (option.disabled) {
            option.style.color = "graytext";
        }
        else {
            option.style.color = "menutext";
        }
    }
}

然后再HTML页面上增加下面的代码

 

 <!--[if lt IE 7]>
 <script type="text/javascript" src="select-option-disabled-emulation.js"></script>
 <![endif]-->

 

在IE6下我们看到，被"disabled"的选项处于关闭状态，用户选择后会自动恢复到前一个状态项。