javascript密码强度判断

-------javascript代码：-------------------<script type="text/javascript">        //CharMode函数         //测试某个字符是属于哪一类.         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         //计算出当前密码当中一共有多少种模式         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);         }         //pwStrength函数         //当用户放开键盘或密码输入框失去焦点时,根据不同的级别显示不同的颜色         function pwStrength(pwd){         O_color="#eeeeee";         L_color="#FF0000";         M_color="#FF9900";         H_color="#33CC00";         if (pwd==null||pwd==''){         Lcolor=Mcolor=Hcolor=O_color;         }         else{         S_level=checkStrong(pwd);         switch(S_level) {         case 0:         Lcolor=Mcolor=Hcolor=O_color;         case 1:         Lcolor=L_color;         Mcolor=Hcolor=O_color;         break;         case 2:         Lcolor=Mcolor=M_color;         Hcolor=O_color;         break;         default:         Lcolor=Mcolor=Hcolor=H_color;         }         }         document.getElementById("strength_L").style.background=Lcolor;         document.getElementById("strength_M").style.background=Mcolor;         document.getElementById("strength_H").style.background=Hcolor;         return;         } </script>

html页面:

<form name=form1 action="" > 输入密码:<input type=password size=10 onKeyUp=pwStrength(this.value) onBlur=pwStrength(this.value)> <br>密码强度: <table width="217" border="1" cellspacing="0" cellpadding="1" bordercolor="#cccccc" height="23" style='display:inline'> <tr align="center" bgcolor="#eeeeee"> <td width="33%" id="strength_L">弱</td> <td width="33%" id="strength_M">中</td> <td width="33%" id="strength_H">强</td> </tr> </table> </form>