jQuery snippet to judge the strength of a password. View the demo of this code snippet http://www.paulund.co.uk/password-strength-indicator-jquery

jquery-password-strength-form.html

<form action="" method="post">
    	<p><label for="passwordInput">Password: <input type="password" id="passwordInput" name="passwordInput"></label></p>
	<p><label for="confirmPasswordInput">Confirm Password: <input type="password" id="confirmPasswordInput" name="confirmPasswordInput"></label></p>
	<p><div class="" id="passwordStrength"></div></p>
	<p><input type="submit" value="Change Password" class="btn"></p>
</form>

jquery-password-strength.js

 $(document).ready(function() {

    $('#passwordInput, #confirmPasswordInput').on('keyup', function(e) {

        if($('#passwordInput').val() == '' && $('#confirmPasswordInput').val() == '')
        {
            $('#passwordStrength').removeClass().html('');

            return false;
        }

     if($('#passwordInput').val() != '' && $('#confirmPasswordInput').val() != '' && $('#passwordInput').val() != $('#confirmPasswordInput').val())
    	{
    		$('#passwordStrength').removeClass().addClass('alert alert-error').html('Passwords do not match!');

        	return false;
    	}

        // Must have capital letter, numbers and lowercase letters
        var strongRegex = new RegExp("^(?=.{8,})(?=.*[A-Z])(?=.*[a-z])(?=.*[0-9])(?=.*\\W).*$", "g");

        // Must have either capitals and lowercase letters or lowercase and numbers
        var mediumRegex = new RegExp("^(?=.{7,})(((?=.*[A-Z])(?=.*[a-z]))|((?=.*[A-Z])(?=.*[0-9]))|((?=.*[a-z])(?=.*[0-9]))).*$", "g");

        // Must be at least 6 characters long
        var okRegex = new RegExp("(?=.{6,}).*", "g");

        if (okRegex.test($(this).val()) === false) {
            // If ok regex doesn't match the password
        	$('#passwordStrength').removeClass().addClass('alert alert-error').html('Password must be 6 characters long.');

        } else if (strongRegex.test($(this).val())) {
            // If reg ex matches strong password
            $('#passwordStrength').removeClass().addClass('alert alert-success').html('Good Password!');
        } else if (mediumRegex.test($(this).val())) {
            // If medium password matches the reg ex
            $('#passwordStrength').removeClass().addClass('alert alert-info').html('Make your password stronger with more capital letters, more numbers and special characters!');
        } else {
            // If password is ok
            $('#passwordStrength').removeClass().addClass('alert alert-error').html('Weak Password, try using numbers and capital letters.');
        }
        
        return true;
    });

});