以下是代码：
<html>
<head>
<title>JS判断密码强度</title>
<script language=javascript>
//判断输入密码的类型
function CharMode(iN){
if (iN>=48 && iN <=57) //数字
return 1;
if (iN>=65 && iN <=90) //大写
return 2;
if (iN>=97 && iN <=122) //小写
return 4;
else
return 8;
}
//bitTotal函数
//计算密码模式
function bitTotal(num){
modes=0;
for (i=0;i<4;i++){
if (num & 1) modes++;
num>>>=1;
}
return modes;
}
//返回强度级别
function checkStrong(sPW){
if (sPW.length<6)
return 0; //密码太短，不检测级别
Modes=0;
for (i=0;i<sPW.length;i++){
//密码模式
Modes|=CharMode(sPW.charCodeAt(i));
}
return bitTotal(Modes);
} //显示颜色
function pwStrength(pwd){
Dfault_color="#eeeeee"; //默认颜色
L_color="#FF0000"; //低强度的颜色，且只显示在最左边的单元格中
M_color="#FF9900"; //中等强度的颜色，且只显示在左边两个单元格中
H_color="#33CC00"; //高强度的颜色，三个单元格都显示
if (pwd==null||pwd==''){
Lcolor=Mcolor=Hcolor=Dfault_color;
}
else{
S_level=checkStrong(pwd);
switch(S_level) {
case 0:
Lcolor=Mcolor=Hcolor=Dfault_color;
break;
case 1:
Lcolor=L_color;
Mcolor=Hcolor=Dfault_color;
break;
case 2:
Lcolor=Mcolor=M_color;
Hcolor=Dfault_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>
</head>
<body>
<form name=form1 action="" >
<table width="250" border="0" cellpadding=2" bordercolor="#eeeeee" style='display:inline'>
<tr>
<td width="40%" align="right">密码:</td>
<td colspan="3" align="left">
<input type=password size=20 onKeyUp=pwStrength(this.value) onBlur=pwStrength(this.value)>
</td>
</tr>
<tr align="center">
<td width="40%" align="right">密码强度:</td>
<td width="20%" id="strength_L" bgcolor="#eeeeee">弱</td>
<td width="20%" id="strength_M" bgcolor="#eeeeee">中</td>
<td width="20%" id="strength_H" bgcolor="#eeeeee">强</td>
</tr>
</table>
</form>
</body>
</html>