2775. 将 undefined 转为 null

2775. 将 undefined 转为 null

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

type Obj1 = Record<string, Value> | Array<Value>
type Obj2 = Record<string, JSONValue> | Array<JSONValue>

// function undefinedToNull<T>(input: T): T {
//     if (Array.isArray(input)) {
//         return input.map((item) =>
//             item === undefined ? null : undefinedToNull(item)
//         ) as any
//     }

//     if (input !== null && typeof input === 'object') {
//         const result: Record<string, any> = {}
//         for (const [key, value] of Object.entries(input)) {
//             result[key] = value === undefined ? null : undefinedToNull(value)
//         }
//         return result as T
//     }

//     return input
// }
function undefinedToNull(obj: Record<any, any>): Record<any, any> {
  if (obj === undefined) return null
  if (typeof obj !== 'object' || typeof obj === null) return obj
  for (const key in obj) {
    obj[key] = undefinedToNull(obj[key])
  }
  return obj
}

/**
 * undefinedToNull({"a": undefined, "b": 3}) // {"a": null, "b": 3}
 * undefinedToNull([undefined, undefined]) // [null, null]
 */