<form method="POST" name="contact">
                    <div class="g-recaptcha"
                         data-sitekey="............."
                         data-callback="onCompleted"
                         data-size="invisible">
                    </div>


                    <div class="col-md-12 text-right inputcontact">
                        <input type="submit" name="submit" value="Verstuur"  class="btn btn-default">
                    </div>
                </form>

$(document).ready(function(){
    $('#vragen').keyup(function(){
        var left = 500 - $(this).val().length;
        if(left < 0){
            left = 0;
        }
        $('#teller').text(left + ' Karakters over');
    });





    $("form[name='contact']").validate({

       rules:{
           naam:{
               required:true,
               minlength:2,
               maxlength:40,
               accept:"[a-z A-Z]+"
           },
           email:{
               required:true,
               maxlength:50,
               email:true
           },
           telefoon:{
               required:false,
               accept:"[0-9 -]+",
               maxlength:15
           },
           vraag:{
               required:true
           }
       },
        messages:{
            naam:{
                minlength:"Dit veld moet minimaal {0} tekens bevatten.",
                accept: "Geen cijfers of speciale tekens."
            },
            telefoon:{
                maxlength: "Maximaal {0} tekens",
                accept: "alleen cijfers en het scheidingsteken: - "
            },
            email:{
                maxlength: "Dit veld mag maximaal {0} tekens bevatten.",
                email:"Dit is geen geldig e-mailadres"
            }
        }






    });

    $("form[name='contact']").submit(function(event) {
        console.log('validation completed.');

        event.preventDefault(); //prevent form submit before captcha is completed
        grecaptcha.execute();
    });

    onCompleted = function() {
        console.log('captcha completed.');
    };
    jQuery.validator.addMethod("accept", function(value, element, param) {
        return this.optional(element) || value.match(new RegExp("^" + param + "$"));
    });
})

if (isset($_POST['submit'])) {
    die("ffffffffffffffffff"); //testing purposes
}