Q:

Ajax not working intermittently on some computers

I guess I'm not up-to-date or am missing something really simple.
I have the javascript code below, which uses ajax to connect to an external php file which reads the form post'd variables and pulls pricing from a sql database and returns the price, which is updated on the current page. The machine I am testing on uses Windows 7 and the latest version of Chrome browser. The ajax call ALWAYS works. I was in a different office yesterday and tested the code on a Windows 10 machine running the latest Chrome browser and the ajax call seems to never work and no price is updated. I also tried the latest Internet explorer browser on the same Windows 10 machine and it did NOT work. I found another Windows 7 machine at the same location using Chrome and it worked fine on it. What's even crazier is this morning, I tried the code on a Windows 10 machine running the latest Chrome and the first time the page loaded it worked but then quit again.
I keep checking the code and don't see anything, as it works fine on some machines. Any ideas or thoughts would greatly be appreciated.
I am using jQuery v1.12.4. I thought maybe this might have an issue so I tried using 3.1.1 even and nothing changed.
What am I missing? How would I be able to debug the ajax call to see what is actually happening on the computer that it isn't working? 
THE JAVASCRIPT CODE:

<script type='text/javascript'>
// Monitor changes to Quantity form field
$('#Quantity').on('keyup', function(event) {
    $.ajax({
        url: 'updatePrice.php',
        type: 'POST',
        contentType: 'application/json; charset=utf-8',
        data: $('#OrderDetails').serialize(),
        datatype: 'json',
        success: function(response) {
            $("#showPrice").text('$' + response);
        }
    });
});

function updatePrice() {
    $.ajax({
        url: 'updatePrice.php',
        type: 'POST',
        contentType: 'application/json; charset=utf-8',
        data: $('#OrderDetails').serialize(),
        datatype: 'json',
        success: function(response) {
            $("#showPrice").text('$' + response);
        }
    });
}
</script>

THE SHORTENED HTML CODE RELATED TO THE JAVASCRIPT:

Quantity<br><input type="text" name="Quantity" id="Quantity" class="textWidth2" value="">

<img src="images/B&WSelected.png" id="BWimage" onclick="changeImage3(); updatePrice();">

<div class="border-top-color quote_panel">
<span class="quote_title">Your Price:</span>
<span id="showPrice" class="quote_price">$0.00</span>
</div>

A:

I finally figured out what was causing the problem I believe. I think it is both 'crossdomain requests' related and encoding issues.
I edited the ajax call by removing the full url (http://www....) from url: and only left the file name and I removed the line
contentType: 'application/json; charset=utf-8',
from the code and now everything seems to work perfectly

function updatePrice() {
    $.ajax({
      url: 'updatePrice.php',
      type: 'POST',
      data: $('#OrderDetails').serialize(),
      datatype: 'json',
      success:function(response){
      $("#showPrice").text('$'+response);
      }
    });
}

