deepCopy & deepMerge Method in ECMAScript 6

deepCopy.js

export function deepCopy(obj) {
  if (typeof obj !== 'object' || obj === null) {
    return obj
  }

  if (obj instanceof Date) {
    return new Date(obj.getTime())
  }

  if (obj instanceof Array) {
    return obj.reduce((arr, item, i) => {
      arr[i] = deepCopy(item)
      return arr
    }, [])
  }

  if (obj instanceof Object) {
    return Object.keys(obj).reduce((newObj, key) => {
      newObj[key] = deepCopy(obj[key])
      return newObj
    }, {})
  }
}

export function deepMerge(obj, ...args) {
  for (let i = 0, l = args.length; i < l; i++) {
    const o = args[i]
    const ks = Object.keys(o)

    for (let j = 0, k = ks.length; j < k; j++) {
      const k = ks[j]

      if (typeof k === 'object') {
        obj[k] = deepCopy(o[k])
      } else {
        obj[k] = o[k]
      }
    }
  }

  return obj
}