Passing XML element to JavaScript function

Question

I am trying to pass on an xml element variable to a JS function and I end up with Uncaught SyntaxError: Unexpected identifier on client-side when pressing the button. The error goes away when I pass other simple variable like integer to the function. Does that mean that it is impossible to pass an XML object to a function? Here's the code.

   function loadXMLDoc() {
  var xmlhttp = new XMLHttpRequest();
  xmlhttp.onreadystatechange = function() {
    if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
      myFunction(xmlhttp);
    }
  };
  xmlhttp.open("GET", "/static/egais_files/ReplyRests.xml", true);
  xmlhttp.send();
}
function myFunction(xml) {
  var i;
  var xmlDoc = xml.responseXML;
  var table="<tr><th></th><th>Alco-code</th></tr>";
  var x = xmlDoc.getElementsByTagName("StockPosition");
  for (i = 0; i <x.length; i++) { 
    table += "<tr>" +
                "<td>" + x[i].getElementsByTagName("AlcCode")[0].childNodes[0].nodeValue + "</td>" + 
                "<td><button onclick = 'populate_ttn1_xml(" + x[i] + ")' type='button' class='btn btn-primary'>OK</button></td>" + 
            "</tr>";
  }
  document.getElementById("egaisResultTable").innerHTML = table;
};
var populate_ttn1_xml = function(x)
{   
    result = 1
}

EDIT: Some more code added. The problem arises when pressing the OK button (function populate_ttn1_xml