search within nested properties of an object, stops searching when hitting a null property — taken from: https://medium.com/javascript-inside/safely-accessing-deeply-nested-values-in-javascript-99bf72a0855a

getPropValue.js

/**
 * search within nested properties of an object, stops searching when hitting a null property
 * e.g. for this.soundCloudAudio._track.user.avatar_url,
 * let avatarUrl = getPropValue( ['_track', 'user', 'avatar_url'], this.soundCloudAudio ) // assigned null if property doesn't exist
 * @param  {Array} pathToProp   the path to a nested prop we hope to find, each step listed as an array value (string for keys, number for indexes)
 * @param  {Object} objectToScan the object to look through for all available properties based on the path above
 * @return {varies}              returns null, or the value found at the requested property
 */
const getPropValue = (pathToProp, objectToScan) =>
  return pathToProp.reduce(
      (step, otherStep) => (step && step[otherStep] ? step[otherStep] : null),
      objectToScan