gistfile1.js

function getElementXPath(elt)
{
     var path = "";
     for (; elt && elt.nodeType == 1; elt = elt.parentNode)
     {
        idx = getElementIdx(elt);
        xname = elt.tagName;
        if (idx > 1) xname += "[" + idx + "]";
        path = "/" + xname + path;
     }
 
     return path.toLowerCase();       
}

function getElementIdx(elt)
{
    var count = 1;
    for (var sib = elt.previousSibling; sib ; sib = sib.previousSibling)
    {
        if(sib.nodeType == 1 && sib.tagName == elt.tagName)     count++
    }
    
    return count;
}

function elementByXpath(xpath)
{
  var result = document.evaluate(xpath, document, null, 7, null);
  return(result.snapshotItem(0));
}

function elementTop(element)
{
  var top = element.offsetTop;
  while (element = element.offsetParent) {
    top += element.offsetTop;
  }
  return(top);
}

var xpath = getElementXPath(window.getSelection().anchorNode.parentNode);
var node  = elementByXpath(xpath);
var top   = elementTop(node);

console.log('XPATH: ' + xpath);
console.log('NODE:  ' + node);
console.log('TOP:   ' + top);