getChangedKeys.js

import { filter, union, keys } from 'lodash'

function changedKeys(o1, o2) {
  return filter(union(keys(o1), keys(o2)), key => o1[key] !== o2[key]).map(key => ({
    [key]: {
      prev: o1[key],
      next: o2[key],
    },
  }))
}