How to Prevent Duplicate Form Submissions

Question

I have simple email script with few forms and I am getting duplicate submissions...

So, what is the easiest way to prevent duplicate submissions?

My code..

<form action="main_contact.php" method="post" name="contact_form">
                  <input type="text" name="contact_name" placeholder="Name">
                  <input type="email" name="contact_email" placeholder="Email">
                  <input type="text" name="contact_subject" placeholder="Subject">
                  <textarea cols="30" name="contact_message" rows="10" placeholder="Your Message"></textarea>
                   <input type="submit" value="Send">  
                </form>

<?php
                  if(isset($_POST['contact_form'])){ 
                    var_dump($_POST);
                  }
                ?>

Have you checked the logs to try and piece together the user journey? — Progrock, Sep 18 '16 at 21:23
What I meant was why is this behaviour happening? Is the user waiting for something to happen, and hitting the button multiple times? Or do the logs or analytics reveal another reason? See also: http://stackoverflow.com/questions/926816/how-to-prevent-form-from-submitting-multiple-times-from-client-side — Progrock, Sep 18 '16 at 21:30

score 1 · Answer 1 · answered Sep 18 '16 at 21:58

1

You can use jQuery to disable submit button after the form has been submitted:

$('form[name="contact_form"]').submit(function(){
    $(this).find('input[type="submit"]').prop('disabled', true);
});

answered Sep 18 '16 at 21:58

Ilya Butorin

11
2

This is a straight forward approach to it. Furthermore, make sure that you are displaying a success message to the user following a submission. Even redirecting to a success page is effective, and can help track conversion. :) – Brian Schroeter Sep 18 '16 at 22:18

score 0 · Answer 2 · answered Sep 19 '16 at 10:45

you just need to disable or make visibility hidden after just click on submit button. fist give a id to the submit button

<input type="submit" value="Send" id="sub_id">

and then make it hidden or disable in javascript once you submit the form

document.getElementById('sub_id').style.visibility='hidden';

score -1 · Answer 3 · answered Sep 18 '16 at 21:09

-1

If you used any framework like Laravel5 or Symfony you would get it "out of the box".

In short: Register a session token and invalidate it after first form submission.

answered Sep 18 '16 at 21:09

jakub wrona

2,212
17
17

Hey.. Its simple email script so there is no MySql.. – John Stuart Sep 18 '16 at 21:11
You don't need MySql to start a session and register a token. – jakub wrona Sep 18 '16 at 21:13

How to Prevent Duplicate Form Submissions

3 Answers3