源自Google的驗證密碼強度

 四種組合指 數字,小寫字母,大寫字母,其它字元

把密碼強度分為四等:

1. 密碼長度小於或等於6位.或者密碼只有一種組合
2. 密碼長度大於6位, 且有兩種組合.
3. 密碼長度大於6位, 且有三種組合.
4. 密碼長度大於6位, 且有四種組合.

如果沒有輸入則返回0

 demo 示範
<table>
    <tbody>
        <tr>
            <td>密碼：</td>
            <td><input id=pwd onkeyup=CreateRatePasswdReq(this); type=password value=""> <span style="FONT-FAMILY: arial,sans-serif">長度必須最少包含 6 個字元。</span>
            <table cellSpacing=0 cellPadding=0 border=0>
                <tbody>
                    <tr>
                        <td vAlign=top noWrap width=0><font face="Arial, sans-serif" size=-1>密碼強度： </font></td>
                        <td vAlign=top noWrap><font face="Arial, sans-serif" color=#808080 size=-1><strong>
                        <div id=passwdRating></div>
                        </strong></font></td>
                    </tr>
                    <tr>
                        <td height=3></td>
                    </tr>
                    <tr>
                        <td colSpan=2>
                        <table id=passwdBar cellSpacing=0 cellPadding=0 width=180 bgColor=#ffffff border=0>
                            <tbody>
                                <tr>
                                    <td id=posBar width=0% bgColor=#e0e0e0 height=4></td>
                                    <td id=negBar width="100%" bgColor=#e0e0e0 height=4></td>
                                </tr>
                            </tbody>
                        </table>
                        </td>
                    </tr>
                </tbody>
            </table>
            </td>
        </tr>
    </tbody>
</table>
<script>

  ratingMsgs = new Array(6);
  ratingMsgColors = new Array(6);
  barColors = new Array(6);
  ratingMsgs[0] = "太短";
  ratingMsgs[1] = "弱";
  ratingMsgs[2] = "一般";
  ratingMsgs[3] = "很好";
  ratingMsgs[4] = "極佳";
  ratingMsgs[5] = "未評級"; //If the password server is down
  ratingMsgColors[0] = "#676767";
  ratingMsgColors[1] = "#aa0033";
  ratingMsgColors[2] = "#f5ac00";
  ratingMsgColors[3] = "#6699cc";
  ratingMsgColors[4] = "#008000";
  ratingMsgColors[5] = "#676767";
  barColors[0] = "#dddddd";
  barColors[1] = "#aa0033";
  barColors[2] = "#ffcc33";
  barColors[3] = "#6699cc";
  barColors[4] = "#008000";
  barColors[5] = "#676767";
  function CreateRatePasswdReq(pwd) {
    if (!isBrowserCompatible) {
      return;
    }
   
   // if(!document.getElementById) return false;
   // var pwd = document.getElementById("pwd");
    if(!pwd) return false; 
    passwd=pwd.value;
    var min_passwd_len = 6; 
    if (passwd.length < min_passwd_len)  {
      if (passwd.length > 0) {
        DrawBar(0);
      } else {
        ResetBar();
      }
    } else {
     //We need to escape the password now so it won't mess up with length test
       rating = checkPasswdRate(passwd);
       DrawBar(rating);
 
    }
  }
 function getElement(name) {
    if (document.all) {
        return document.all(name);
    }
    return document.getElementById(name);
}
 
  function DrawBar(rating) {
    var posbar = getElement('posBar');
    var negbar = getElement('negBar');
    var passwdRating = getElement('passwdRating');
    var barLength = getElement('passwdBar').width;
    if (rating >= 0 && rating <= 4) {  //We successfully got a rating
      posbar.style.width = barLength / 4 * rating + "px";
      negbar.style.width = barLength / 4 * (4 - rating) + "px";
    } else {
      posbar.style.width = "0px";
      negbar.style.width = barLength + "px";
      rating = 5; // Not rated Rating
    }
    posbar.style.background = barColors[rating];
    passwdRating.innerHTML = "<font color='" + ratingMsgColors[rating] +
                             "'>" + ratingMsgs[rating] + "</font>";
  }
  
  //Resets the password strength bar back to its initial state without any message showing.
  function ResetBar() {
    var posbar = getElement('posBar');
    var negbar = getElement('negBar');
    var passwdRating = getElement('passwdRating');
    var barLength = getElement('passwdBar').width;
    posbar.style.width = "0px";
    negbar.style.width = barLength + "px";
    passwdRating.innerHTML = "";
  }
  /* Checks Browser Compatibility */
  var agt = navigator.userAgent.toLowerCase();
  var is_op = (agt.indexOf("opera") != -1);
  var is_ie = (agt.indexOf("msie") != -1) && document.all && !is_op;
  var is_mac = (agt.indexOf("mac") != -1);
  var is_gk = (agt.indexOf("gecko") != -1);
  var is_sf = (agt.indexOf("safari") != -1);
  function gff(str, pfx) {
    var i = str.indexOf(pfx);
    if (i != -1) {
      var v = parseFloat(str.substring(i + pfx.length));
      if (!isNaN(v)) {
      return v;
      }
    }
    return null;
  }
  function Compatible() {
    if (is_ie && !is_op && !is_mac) {
      var v = gff(agt, "msie ");
      if (v != null) {
        return (v >= 6.0);
      }
    }
    if (is_gk && !is_sf) {
      var v = gff(agt, "rv:");
      if (v != null) {
         return (v >= 1.4);
      } else {
         v = gff(agt, "galeon/");
         if (v != null) {
           return (v >= 1.3);
         }
      }
    }
    if (is_sf) {
      var v = gff(agt, "applewebkit/");
      if (v != null) {
        return (v >= 124);
      }
    }
    return false;
  }
 
  /* We also try to create an xmlhttp object to see if the browser supports it */
  var isBrowserCompatible = Compatible();

//CharMode函數 
//測試某個字元是屬於哪一類. 
function CharMode(iN){ 
if (iN>=48 && iN <=57) //數字 
return 1; 
if (iN>=65 && iN <=90) //大寫字母 
return 2; 
if (iN>=97 && iN <=122) //小寫 
return 4; 
else 
return 8; //特殊字元 
} 
//bitTotal函數 
//計算出當前密碼當中一共有多少種模式 
function bitTotal(num){ 
modes=0; 
for (i=0;i<4;i++){ 
if (num & 1) modes++; 
num>>>=1; 
} 
return modes; 
} 
//checkStrong函數 
//返回密碼的強度層級 
function checkPasswdRate(sPW){ 
if (sPW.length<=4) 
return 0; //密碼太短 
Modes=0; 
for (i=0;i<sPW.length;i++){ 
//測試每一個字元的類別並統計一共有多少種模式. 
Modes|=CharMode(sPW.charCodeAt(i)); 
} 
return bitTotal(Modes); 
} 
 

</script>

 

demo 示範

密碼：	長度必須最少包含 6 個字元。 密碼強度：