php and javascript form validation issue

I have created a form using bootstrap and am using javascript for form validation and then a php script to grab the post data and display it
the basic structure is the following and I have made this as minimal as I could to address this specific issue. The issue I am having is that the script to check for the form validation works perfectly in the <script> tags at the end of the body, but instead of preventing the page from being submitted as it should it still processes to the next page with the form's contents that are being made through the php post action when the form is indeed not filled out correctly.
Why is this? Should the form validation still not stop the page from moving on to the post data since the validation is returning false if the form has not been submitted correctly. All the form validation alerts pop up correctly and I;m getting no console errors after checking, or do I need to perform an additional check to only process the post data if the form is valid?
<html>
   other tags.....
   <body>
      <form name = "OrderForm" action = "process_order.php" onsubmit = "orderbutton" method = "post">
a bunch of content, divs, checkboxes, etc
      </form>
   </body>
   <script>

function CheckForm() {
var Name = document.getElementById("Name");
var fries = document.forms.OrderForm.FryRadio;
var fryyes = fries[0].checked
var fryno = fries[1].checked

var bool = true;

if ((Name.value == "" || Name.value == "Name") || (!(document.getElementById("SandwichRadio").checked || document.getElementById("WrapRadio").checked)))  {
bool = false;
}

else if (!(fryyes || fryno)) {
bool = false;
}

if (!(bool)) {
alert("Please fill out all of the required fields.");
return false;
}
else {
alert("Your order is being submitted");
console.log("Submitted")
}

};

    </script>
</html>

You should call function on submit , I dont know what are you doing with current onsubmit='...'
So use following, call function when you submit the form.
  <form name = "OrderForm" action = "process_order.php" onsubmit = "return CheckForm()" method = "post">
      a bunch of content, divs, checkboxes, etc
  </form>

For demo : Check Fiddle