抽象一个类型判断库

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export function type(x) {
  const t = typeof x
  if (x === null) {
    return 'null'
  }
  if (t !== 'object') {
    return t
  }
  const toString = Object.prototype.toString
  const innerType = toString.call(x).slice(8, -1)
  const innerLowType = innerType.toLowerCase()

  if (['String', 'Boolean', 'Number'].includes(innerType)) {
    return innerType
  }

  if (typeof x?.constructor?.name === 'string') {
    return x.constructor.name
  }

  return innerLowType
}