Check password safety with JavaScript while typing

You can show password strength to your visitors while typing before even submitting the page to the webserver. There are four character groups: letters, caps, numbers and symbols. A password which is longer than 7 characters and contains at least one character from each group is strong vz537gnjua. A password which is at least 8 character long and has all characters from one group is weak (but not very weak). A password which contains all characters from one group and at least 20 characters long is also strong. Rules are easy: longer is better, combined is the best.

Demo:

Type your password!

Strong Password Examples:

Qw#45678
Qw4567890123
a234567890123456
12345678901234567890
abcdefghijklmnoprstu

Code:

<script language="javascript">

function check_password_safety(pwd){

var msg = "";
var points = pwd.length;
var password_info = document.getElementById('password_info');

var has_letter		= new RegExp("[a-z]");
var has_caps		= new RegExp("[A-Z]");
var has_numbers		= new RegExp("[0-9]");
var has_symbols		= new RegExp("\\W");

if(has_letter.test(pwd)) 	{ points += 4; }
if(has_caps.test(pwd)) 		{ points += 4; }
if(has_numbers.test(pwd)) 	{ points += 4; }
if(has_symbols.test(pwd)) 	{ points += 4; }


if( points >= 24 ) {
	msg = '<span style="color: #0f0;">Your password is strong!</span>';
} else if( points >= 16 ) {
	msg = '<span style="color: #00f;">Your password is medium!</span>';
} else if( points >= 12 ) {
	msg = '<span style="color: #fa0;">Your password is weak!</span>';
} else {
	msg = '<span style="color: #f00;">Your password is very weak!</span>';
}

password_info.innerHTML = msg ;
}


</script>

<input type="text" name="pwd" id="pwd" size="20" onkeyup="return check_password_safety(this.value);" />

<span id="password_info"><b>Type your password!</b></span>