File upload using ajax and JavaScript function

Need a big favor! I'm trying to send uploaded file using JavaScript & Ajax, however not getting any success.

I want that when I upload the file, it will call the function myFunction(), and send the file to the PHP path(ajax.php) I've set.

Below is the code I've so far.

<script>
   function myFunction() {
      var x = document.getElementById("up");
      $.ajax({
         type: 'GET',
         url: 'ajax.php',
         data: {},
         beforeSend: function() {},
         success: function(data) {
            alert(data);
         }
      });
   }
</script>
<input type="file" name="images" id="up" onchange="myFunction()" />