网上转载的一段代码，留着以后用，

js文件：

//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<=4)
return 0; //密码太短
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){
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;
}

页面：

<td>
<table border="0"><tr >
<td style=" padding: 0px;border-top-width: 0px; border-right: #ff0000 0px solid; border-left: #ff0000 0px solid; border-top-color: #ff0000; border-bottom: #ff0000 0px solid;">

<input id="password"name="password" type=password size=8 onKeyUp=pwStrength(this.value) onBlur=pwStrength(this.value)></td>
<td style=" padding: 0px;border-top-width: 0px; border-right: #ff0000 0px solid; border-left: #ff0000 0px solid; border-top-color: #ff0000; border-bottom: #ff0000 0px solid;">
<span id="sp_6" style="color:red;" ></span>
</td>
<td style=" padding: 0px;border-top-width: 0px; border-right: #ff0000 0px solid; border-left: #ff0000 0px solid; border-top-color: #ff0000; border-bottom: #ff0000 0px solid;">
<table width="500" border="0" cellspacing="0" cellpadding="1" bordercolor="#eeeeee" height="20" style=‘display:inline‘>
<tr align="center" bgcolor="#f5f5f5">
<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>
</td>
</tr>
</table>
</td>