;(function () {
var wrapper = document.getElementById("wrapper")
var els = Array.prototype.slice.call(wrapper.getElementsByTagName("*"), 0)
  .filter(function (el) {
    return el.parentNode === wrapper
        && el.tagName.match(/H[1-6]/)
        && el.id
  })
var l = 2
  , toc = document.createElement("ul")
toc.innerHTML = els.map(function (el) {
  var i = el.tagName.charAt(1)
    , out = ""
  while (i > l) {
    out += "<ul>"
    l ++
  }
  while (i < l) {
    out += "</ul>"
    l --
  }
  out += "<li><a href='#" + el.id + "'>" +
    ( el.innerText || el.text || el.innerHTML)
    + "</a>"
  return out
}).join("\n")
toc.id = "toc"
document.body.appendChild(toc)
})();