Simple jQuery form validation

The form goes nowhere, but shows some form input validators both serverside and browserside.

Incorrect values range from 0-6 characters and 12+ characters. Additional validations can easily be added

The server returns a JSON object which the script eval's

feel free to use the code. A link back would be nice

Below is the contents of ajax.php: ( do not write php like this, its just for illustrative purposes )

$input = $_REQUEST['id'];
$value = $_REQUEST['value'];

if (strlen($value) < 6) {
echo "{ id: '$input', value: '$value', success: false, msg: 'Your Username is too short (more than 6 characters) Please try again'}";
} else if (strlen($value) > 12) {
echo "{ id: '$input', value: '$value', success: false, msg: 'Your Username is too long (less than 12 characters) Please try again'}";
} else {
echo "{ id: '$input', value: '$value', success: true, msg: 'woo!'}";
}