javascript - How to find the nearest common ancestors of two or more nodes?

Question

Users selects two or more elements in a HTML page. What i want to accomplish is to find those elements' common ancestors (so body node would be the common ancestor if none found before) ?

P.S: It can be achieved with XPath but it is not a preferable option for me. Also it may be found with css selector parsing but i think it is a dirty method (?)

Thank you.

Answer 1

Here's a pure JavaScript version that is a little more efficient.

function parents(node) {
  var nodes = [node]
  for (; node; node = node.parentNode) {
    nodes.unshift(node)
  }
  return nodes
}

function commonAncestor(node1, node2) {
  var parents1 = parents(node1)
  var parents2 = parents(node2)

  if (parents1[0] != parents2[0]) throw "No common ancestor!"

  for (var i = 0; i < parents1.length; i++) {
    if (parents1[i] != parents2[i]) return parents1[i - 1]
  }
}