Play with jQuery to realize the password strength prompt information function when registering as a member

<p><span>设置密码：</span><input type="password" id="external_regist_password1" name="password1" value="" /><b>*</b>
<span id="password1_bg" class="bg_rt" style="display:none"></span>
</p>
<p class="mima_qd" id="password1_strength" style="display:none">
 <span class="mm_strength"><em>密码强度</em>
   <i class="password_qd">
    <span class="password_bg" id="strength_L"></span>
    <span class="password_bg" id="strength_M"></span>
    <span class="password_bg" id="strength_H"></span>
   </i>
  <em id="pw_check_info"></em>
</span>
</p>
<p class="tishi_wr" id="password1_info"></p>

//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
    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.
    //charCodeAt():返回unicode编码的值
    Modes|=CharMode(sPW.charCodeAt(i)); //测试某个字符属于哪一类
  }
  return bitTotal(Modes);//计算出当前密码当中一共有多少种模式
}
//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){
  var modes=0;
  for (i=0;i<4;i++){
    if (num & 1) modes++;
    num>>>=1;
  }
  return 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){
  var O_color="#eeeeee";
  var L_color="#FF4040";
  var M_color="#FF9900";
  var H_color="#33CC00";
  var info = "";
  if (pwd==null||pwd==&#39;&#39;){
    Lcolor=Mcolor=Hcolor=O_color;
  } else {
    S_level=checkStrong(pwd);//检测密码的强度
    switch(S_level) {
       case 0:
         Lcolor=L_color;
         Mcolor=Hcolor=O_color;
         info = "弱";
         break;
       case 1:
         Lcolor=L_color;
         Mcolor=Hcolor=O_color;
         info = "弱";
         break;
       case 2:
         Lcolor=Mcolor=M_color;
         Hcolor=O_color;
         info = "中";
         break;
       default:
         Lcolor=Mcolor=Hcolor=H_color;
         info = "强";
       }
     }
   $("#strength_L").css("background", Lcolor);
   $("#strength_M").css("background", Mcolor);
   $("#strength_H").css("background", Hcolor);
   $("#pw_check_info").html(info);//密码强度提示信息
   return;
}