form validation using ajax with regex

Question

Right now i am using ajax to get the value from input field on key press and match it with the data in mysql,if the data is unique then it will make the border green and mark tick else red border and cross. now i want to add regex to validate the input and restrict it.

function username_check() {
        var username = $('#warden_id').val();
        if (username == "" || username.length < 4) {
            $('#warden_id').css('border', '1px #CCC solid');
            $('#tick').hide();
        } else {

            jQuery.ajax({
                type: "POST",
                url: "check.php",
                data: 'username=' + username,
                cache: false,
                success: function (response) {
                    if (response == 1) {
                        $('#warden_id').css('border', '1px #C33 solid');
                        $('#tick').hide();
                        $('#cross').fadeIn();
                    } else {
                        $('#warden_id').css('border', '1px #090 solid');
                        $('#cross').hide();
                        $('#tick').fadeIn();
                    }

                }
            });
        }

regex i want to use to validate data

/^[a-zA-Z\s]+$/

Answer 1

Just for information you should not validate User code on the clientside. Always treat input from the client as evil

I changed the regex so that the min length (username.length < 4) of the Username is included

 function username_check() {
    var username = $('#warden_id').val();

    // if / else has been turned
    if (username.match(/^[a-zA-Z\s]{4,}$/)) {
        ...
    } else {
        $('#warden_id').css('border', '1px #CCC solid');
        $('#tick').hide();
    }
     ...

...