var getElementsByClassName = function(className) {
  const myNodes = [];

  function innerFn(node) {
    if (node.classList && node.classList.value.indexOf(className) > -1) {
      myNodes.push(node)
    }
    node.childNodes.forEach((child) => innerFn(child))
  }
  innerFn(document.body)

  return myNodes;
};