2755. 深度合并两个对象

2755. 深度合并两个对象

type JSONValue =
  | null
  | boolean
  | number
  | string
  | JSONValue[]
  | { [key: string]: JSONValue }
  | null
  | boolean
  | number
  | string
  | JSONValue[]
  | { [key: string]: JSONValue }

type JSONObject = { [key: string]: JSONValue }

function isObject(value: JSONValue): value is JSONObject {
  return typeof value === 'object'
}

const type = (obj: any) => Object.prototype.toString.call(obj).slice(8, -1)

function deepMerge(obj1: JSONValue, obj2: JSONValue): JSONValue {
  if (obj1 === null) return obj2
  if (type(obj1) !== type(obj2)) return obj2

  if (Array.isArray(obj1) && Array.isArray(obj2)) {
    const result: JSONValue = [...obj1]
    for (let i = 0; i < obj2.length; i++) {
      if (isObject(result[i])) {
        result[i] = deepMerge(result[i], obj2[i])
      } else {
        result[i] = obj2[i]
      }
    }
    return result
  }

  if (isObject(obj1) && isObject(obj2)) {
    const result: JSONObject = { ...obj1 }
    for (const key in obj2) {
      if (key in obj1) {
        result[key] = deepMerge(obj1[key], obj2[key])
      } else {
        result[key] = obj2[key]
      }
    }
    return result
  }

  return obj2
}