在客户端验证密码强度,兼容FireFox和IE

0. 密码为空
1. 密码长度小于六位.或者密码只有一种组合
2. 密码长度大于五位, 且有两种组合.
3. 密码长度大于五位, 且有三种组合.
4. 密码长度大于五位, 且有四种组合.
<script language="JavaScript">
function EvaluatePassword(word)
{
    if (word == "")
    {
        return 0;
    }
    else if (word.length < 6)
    {
        return 1;
    }
    else
    {
        return word.match(/[a-z](?![^a-z]*[a-z])|[A-Z](?![^A-Z]*[A-Z])|\d(?![^\d]*\d)|[^a-zA-Z\d](?![a-zA-Z\d]*[^a-zA-Z\d])/g).length;
    }
}
var test = new Array("", "a1_", "abcdef", "abcde123", "ads23%", "aA1B2^&2");
for(var i in test)
{
    document.write(test[i] + " 的密码强度为" + EvaluatePassword(test[i]) + "<br>");
}
</script> 
                                                                        转自 http://www.cnblogs.com/0009/