Safely retrieve a value from a nested object with a path like 'a.b.c'

valueAtPath.js

/**
 * Safely retrieve a value from a nested object using a string path such as
 * 'a.b.c' or an array ['a', 'b', 'c'].
 */
function valueAtPath (obj, path) {
  if (!Array.isArray(path)) {
    if (!path) return obj
    path = path.split('.')
  }

  if (!path.length)
    return obj
  else if (path.length === 1)
    return obj ? obj[path[0]] : undefined
  else
    return valueAtPath(obj[path[0]], path.slice(1))
}