2823. 深度对象筛选

2823. 深度对象筛选

type JSONValue =
  | null
  | boolean
  | number
  | string
  | JSONValue[]
  | { [key: string]: JSONValue }
type Obj = Record<string, JSONValue> | Array<JSONValue>

const isObject = (obj: any) => typeof obj === 'object' && obj !== null
function deepFilter(obj: Obj, fn: Function): Obj | undefined {
  if (!isObject(obj)) return fn(obj) ? obj : undefined

  if (Array.isArray(obj)) {
    let i = 0
    while (i < obj.length) {
      const val = deepFilter(obj[i] as any, fn)
      if (val === undefined) {
        obj.splice(i, 1) // 原地删除无效值
      } else {
        obj[i] = val
        i++
      }
    }
    return obj.length > 0 ? obj : undefined
  }

  for (const key in obj) {
    const val = obj[key]
    const filtered = deepFilter(val as any, fn)
    if (filtered === undefined) {
      delete obj[key]
    } else {
      obj[key] = filtered
    }
  }

  return Object.keys(obj).length > 0 ? obj : undefined
}