Javascript

$(document).ready(function(){

        $('#contact_form').submit(function(event){

            /* stop form from submitting normally */
            event.preventDefault();

            // Variable declaration
            var name = $('#name').val();
            var email = $('#email').val();
            var subject = $('#subject').val();
            var message = $('#message').val();

           // Disable submit button just after the form processed 1st time successfully.
            $('#submit').attr({'disabled' : 'true', 'value' : 'Sending...' });

            /* Post Ajax function of jQuery to get all the data from the submission of the form as soon as the form sends the values to email.php*/
            $.post("php/function/email.php", $("#contact_form").serialize(),function(result){
                //Check the result set from email.php file.
                if(result == 'sent'){
                    //If the email is sent successfully, remove the submit button
                     $('#submit').remove();
                    //Display the success message
                    $('#success').fadeIn(500);
                }else{
                    //Display the error message
                    $('#error').fadeIn(500);
                    // Enable the submit button again
                    $('#submit').removeAttr('disabled').attr('value', 'Send Message');
                }
            });
            }
        });
    );