deepClone

function deepClone(obj) {
  if (typeof obj !== 'object') return obj
  if (obj === null) return null
  if (obj instanceof Date) return new Date(obj)
  if (obj instanceof RegExp) return new RegExp(obj)
  if (obj instanceof Array) {
    let arr = []
    for (let i in obj) {
      arr[i] = deepClone(obj[i])
    }
    return arr
  }
  var o = {}
  for (var attr in obj) {
    o[attr] = deepClone(obj[attr])
  }
  return o
}