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 
} 

//bitTotal函数 
function bitTotal(num) { 
           modes=0; 
            for (i=0;i<4;i++){ 
            if (num & 1) modes++; 
             num>>>=1; 
             } 
             return modes; 
} 

//checkStrong函数 
//返回密码的强度级别 
function checkStrong(sPW){ 
            if (sPW.length<=4) 
            return 0; //密码太短 
            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)); 
            } 

        return bitTotal(Modes); 
} 

function checkPassStrong(o){
		var strong = checkStrong($(o).val());
								
		$(o).removeClass('inputpass_0 inputpass_1 inputpass_2 inputpass_3').addClass('inputpass_'+strong);
}