Deep Defaults function in JavaScript

deepDefaults.js

const defaultPredicate = (x) => x === null || x === undefined

const deepDefaults = (target, defaults, predicate = defaultPredicate) => {
  if (Object(target) !== target) return Object.assign({}, defaults)

  return Object.keys(defaults).reduce((acc, key) => {
    if (Object(defaults[key]) === defaults[key]) {
      acc[key] = deepDefaults(target[key] || {}, defaults[key], predicate)
    } else {
      acc[key] = predicate(target[key], key) ? defaults[key] : target[key]
    }

    return acc
  }, {
    ...target,
  })
}

export default deepDefaults