Submit form on select change via AJAX - ajax

Question

Let's say I have this form :
<form action="Change-status.php" method="post">
<select class="changeStatus" name="changeStatus">
<option value="0">Starting</option>
<option value="1">Ongoing</option>
<option value="2">Over</option>
</select>
<input class="projectId" type="hidden" name="projectId" value="<?php echo $data['id'];?>"/>
</form>
I am currently using this script to submit the form, but it implies refreshing :
$('select').change(function ()
{
$(this).closest('form').submit();
});
What I want to do is to send the form on select change without refreshing the page. I know I have to use AJAX to do so but I couldn't exactly figure out how to implement it.
Could you orient me on how to do this?
Thanks for your help.
EDIT :
After taking comments into consideration, I ended up with the following code :
Html :
<form action="" method="post">
<select class="changeStatus" name="changeStatus">
<option value="0">Starting</option>
<option value="1">Ongoing</option>
<option value="2">Over</option>
</select>
<input class="projectId" type="hidden" name="projectId" value="<?php echo $data['id'];?>"/>
</form>
JS :
$(document).ready(function() {
$('select.changeStatus').change(function(){
$.ajax({
type: 'POST',
url: 'Change-status.php',
data: {selectFieldValue: $('select.changeStatus').val(), projectId: $('input[name$="projectId"]').val()},
dataType: 'html'
});
});
});
PHP :
<?php
include('../Include/Connect.php');
$changeStatus=$_POST['selectFieldValue'];
$id=$_POST['projectId'];
$sql='UPDATE project SET progress="'.$changeStatus.'" WHERE id="'.$id.'"';
mysql_query($sql) or die("Erreur: ".mysql_error());
?>

Answer 1

Getting cross browser onchange events and AJAX requests working isn't trivial. I'm recommend you use a javascript framework of some kind, which abstracts away all of the cross browser issues so you don't have to worry about them.
Try a js framework
Jquery is just one such framework which has methods such as .change() which attaches a handler to the change event for elements like <select> and .get() which performs a GET request.
Here's a little bit of code to get you started:-
// The $ is the shorthand for a jquery function, you can then use jquery
// selectors which are essentially the same as css selectors, so here
// we select your select field and then bind a function to
// it's change event handler
$('select.changeStatus').change(function(){
// You can access the value of your select field using the .val() method
alert('Select field value has changed to' + $('select.changeStatus').val());
// You can perform an ajax request using the .ajax() method
$.ajax({
type: 'GET',
url: 'changeStatus.php', // This is the url that will be requested
// This is an object of values that will be passed as GET variables and
// available inside changeStatus.php as $_GET['selectFieldValue'] etc...
data: {selectFieldValue: $('select.changeStatus').val()},
// This is what to do once a successful request has been completed - if
// you want to do nothing then simply don't include it. But I suggest you
// add something so that your use knows the db has been updated
success: function(html){ Do something with the response },
dataType: 'html'
});
});
Some references that will be better than my explanations
Please note for this code to work you will need to include the jquery library on you page with a <script> tag.
See here for a quick start guide on using jquery
And here for a beginners tutorial on how to use jquery's ajax() method