验证密码强度js

<script language="javascript">
    
    function allNumber(v)
    {
        var reg = /^[0-9]*$/;
        if(reg.test(v))
        {    
            return true;
        }
        return false;
    }
    
    function CharMode(iN){
        if(iN>=48 && iN<=57)//数字
            return 1;
        if(iN>=65 && iN<=90)//大写字母
            return 2;
        if(iN>=97 && iN<=122)//小写
            return 4;
        else
            return 8;//特殊字符
    }

    //计算出当前密码当中一共有多少种模式
    function bitTotal(num){
        var modes=0;
        for(i=0;i<4;i++){
            if(num&1)
                modes++;
            num >>=1;
        }
        return    modes;
    }
        
    //返回密码的强度级别
    function checkStrong(sPW){
        if(sPW.length<8)
            return 0;//密码太短 
        var Modes=0;
        for(i=0;i<sPW.length;i++){
        //测试每一个字符的类别并统计一共有多少种模式.
        Modes|=CharMode(sPW.charCodeAt(i));
        }
    //    alert(bitTotal(Modes));
        return bitTotal(Modes);
    }

    
    function showStrongPic()
    {
        var v = document.getElementById('new_passwd').value;
        var m = checkStrong(v);
        if(m < 2)
        {
            document.getElementById('lowPic').style.display="";
            document.getElementById('midPic').style.display="none";
            document.getElementById('highPic').style.display="none";
        }
        else if(m==2)
        {
            document.getElementById('lowPic').style.display="none";
            document.getElementById('midPic').style.display="";
            document.getElementById('highPic').style.display="none";
        }
        else 
        {
            document.getElementById('lowPic').style.display="none";
            document.getElementById('midPic').style.display="none";
            document.getElementById('highPic').style.display="";
        }
    }
    
    function checkForm()
    {
        v = document.getElementById('new_passwd').value;
        if(v=="")
        {
            alert("您尚未填写新密码。");
            select_focus('new_passwd');
            return false;
        }
        if(v.length < 8 || allNumber(v) || v.length > 16)
        {        
            alert("新密码格式非法,密码由8-16个字符组成，区分大小写（不能是纯数字）。");
            select_focus('new_passwd');
            return false;
        }

        var w = document.getElementById('new_passwd1').value;
        if(w == "")
        {
            alert("您尚未重复填写新密码。");
            select_focus('new_passwd');
            return false;
        }
        if(w != v)
        {
            alert("两次输入的密码不匹配，请重新输入。");
            select_focus('new_passwd');
            return false;
        }
        document.myform.submit();
    }
</script>