How can i get ip via js and assign variable

[sosenmann]

<script type="application/javascript">
  $(function() {
    $.getJSON("https://api.ipify.org?format=jsonp&callback=?",
      function(json) {
        document.write("My public IP address is: ", json.ip);
      }
    );
  });
</script>

how can i assign json.ip a variable that i can use outside the function and can make a ajax request