html.js

function (
  a, // A Nodelist whichto use as root
  b, // iterate-placeholder
  c, // elem-placeholder
  d, // tags-placeholder
  e, // tag-placeholder
  f  // parent-placeholder
) {
  for (b = 0; c = a[b++];

    // parent has already the same `tagName` as property
    // so there is more than one element in the tree
    (f = c.parentNode)[e] && f[d].push(c) ||

    // otherwise add/assign an array
    // containing the element
    (f[d] = [c]),

    // assign the single node to the parent-node
    f[e] = c)

  d = (e = c.tagName.toLowerCase()) + 's'
}