various view utilities in ES6

view-utils.js

const updateActive = (node) => {
  // remove active class from all items
  Array.prototype.forEach.call(node.parentNode.children, (e) => {
    e.className = e.className.split(' active').join('');
  });

  // add active class to correct item
  node.className = node.className + ' active';
}

const locationFromTop = (element) => {
  let rect = element.getBoundingClientRect();
  let positionTop = rect.top + document.body.scrollTop;
  return positionTop + 1;
}

// returns object
const getElementLocation = (className) => {
  let elements = document.getElementsByClassName(className);
  let elementDetails = {};

  Array.prototype.forEach.call(elements, (e) => {
    let positionTop = locationFromTop(e);
    let newClassName = e.className.split(className).join('');
    elementDetails[e.title] = { positionTop, newClassName };
  });

  return elementDetails;
}