js判断密码强度

<form name="form1" action="">
密码:<input type="password" size="8" onkeyup="pwStrength(this.value)" onblur="pwStrength(this.value)">
<br>
密码强度:
<table width="220px" border="1" cellspacing="0" cellpadding="1" bordercolor="#eeeeee" height="22px">
<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>
</form>

function pwdStrength(pwd) {
O_color = "#eeeeee";
L_color = "#FF0000";
M_color = "#FF9900";
H_color = "#33CC00";
var level = 0, strength = "O";
if (pwd == null || pwd == '') {
strength = "O";
Lcolor = Mcolor = Hcolor = O_color;
}
else {
var mode = 0;
if (pwd.length <= 4)
mode = 0;
else {
for (i = 0; i < pwd.length; i++) {
var charMode, charCode;
charCode = pwd.charCodeAt(i);
// 判断输入密码的类型
if (charCode >= 48 && charCode <= 57) //数字
charMode = 1;
else if (charCode >= 65 && charCode <= 90) //大写
charMode = 2;
else if (charCode >= 97 && charCode <= 122) //小写
charMode = 4;
else
charMode = 8;
mode |= charMode;
}
// 计算密码模式
level = 0;
for (i = 0; i < 4; i++) {
if (mode & 1)
level++;
mode >>>= 1;
}
}
switch (level) {
case 0:
strength = "O";
Lcolor = Mcolor = Hcolor = O_color;
break;
case 1:
strength = "L";
Lcolor = L_color;
Mcolor = Hcolor = O_color;
break;
case 2:
strength = "M";
Lcolor = Mcolor = M_color;
Hcolor = O_color;
break;
default:
strength = "H";
Lcolor = Mcolor = Hcolor = H_color;
break;
}
}
document.getElementById("strength_L").style.background = Lcolor;
document.getElementById("strength_M").style.background = Mcolor;
document.getElementById("strength_H").style.background = Hcolor;
return strength;
}