Function clone

packages/utils/src/helpers.ts:201–257

(
  val: T,
  seen: WeakMap<any, any>,
  options: CloneOptions = defaultCloneOptions,
)

}

export function clone<T>(
  val: T,
  seen: WeakMap<any, any>,
  options: CloneOptions = defaultCloneOptions,
): T {
  let k: any, out: any
  if (seen.has(val)) {
    return seen.get(val)
  }
  if (Array.isArray(val)) {
    out = Array.from({ length: (k = val.length) })
    seen.set(val, out)
    while (k--) {
      out[k] = clone(val[k], seen, options)
    }
    return out as any
  }

  if (Object.prototype.toString.call(val) === '[object Object]') {
    out = Object.create(Object.getPrototypeOf(val))
    seen.set(val, out)
    // we don't need properties from prototype
    const props = getOwnProperties(val)
    for (const k of props) {
      const descriptor = Object.getOwnPropertyDescriptor(val, k)
      if (!descriptor) {
        continue
      }
      const cloned = clone((val as any)[k], seen, options)
      if (options.forceWritable) {
        Object.defineProperty(out, k, {
          enumerable: descriptor.enumerable,
          configurable: true,
          writable: true,
          value: cloned,
        })
      }
      else if ('get' in descriptor) {
        Object.defineProperty(out, k, {
          ...descriptor,
          get() {
            return cloned
          },
        })
      }
      else {
        Object.defineProperty(out, k, {
          ...descriptor,
          value: cloned,
        })
      }
    }
    return out
  }

  return val
}