Micro function that gives xpath by element and elements by xpath.

xpath.js

function xpath(el) {
  if (typeof el == "string") return document.evaluate(el, document, null, 0, null)
  if (!el || el.nodeType != 1) return ''
  if (el.id) return "//*[@id='" + el.id + "']"
  var sames = [].filter.call(el.parentNode.children, function (x) { return x.tagName == el.tagName })
  return xpath(el.parentNode) + '/' + el.tagName.toLowerCase() + (sames.length > 1 ? '['+([].indexOf.call(sames, el)+1)+']' : '')
}

// Usage:

// Getting xpath for node:
var xp = xpath(elementNode)

// Executing xpath:
var iterator = xpath("//h2")
var el = iterator.iterateNext();
while (el) {
  // work with element...
  el = iterator.iterateNext();
}

The code doesn't work in IE 11.

When el is HTMLHtmlElement, el.parentNode.children is undefined, thus line 5 throws exception.

My suggestion is to change the bottom part to

if (el.parentNode.nodeType === 1)
{
    var sames = [].filter.call(el.parentNode.children, function(x) { return x.tagName === el.tagName });
    return getSelector(el.parentNode) + '/' + el.tagName.toLowerCase() + (sames.length > 1 ? '[' + (sames.indexOf(el) + 1) + ']' : '');
} else
    return el.tagName.toLowerCase();

Why is the iterator needed? Shouldn't the function always lead to a single element?

BTW, thanks for this amazing piece of cake! It is working good so far.

Works great! Thank you so much

ps: as xpath isn't truly unique, got any thoughts on making it unique?
I'm thinking something like... combining xpath + href + css selectors to make a unique generated ID etc.