Find comments inside of a DOM element

index.js

const findComments = function (el) {
  var arr = [];
  for (var i = 0; i < el.childNodes.length; i++) {
    var node = el.childNodes[i];
    if (node.nodeType === 8) {
      arr.push(node);
    } else {
      arr.push.apply(arr, findComments(node));
    }
  }
  return arr;
};