使用JavaScript判断密码强度

HTML代码

<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>

JavaScript代码

<script language=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>