Function deepClone

packages/db/src/proxy.ts:514–613

* Deep clones an object while preserving special types like Date and RegExp

(
  obj: T,
  visited = new WeakMap<object, unknown>(),
)

 */

function deepClone<T extends unknown>(
  obj: T,
  visited = new WeakMap<object, unknown>(),
): T {
  // Handle null and undefined
  if (obj === null || obj === undefined) {
    return obj
  }

  // Handle primitive types
  if (typeof obj !== `object`) {
    return obj
  }

  // If we've already cloned this object, return the cached clone
  if (visited.has(obj as object)) {
    return visited.get(obj as object) as T
  }

  if (obj instanceof Date) {
    return new Date(obj.getTime()) as unknown as T
  }

  if (obj instanceof RegExp) {
    return new RegExp(obj.source, obj.flags) as unknown as T
  }

  if (Array.isArray(obj)) {
    const arrayClone = [] as Array<unknown>
    visited.set(obj as object, arrayClone)
    obj.forEach((item, index) => {
      arrayClone[index] = deepClone(item, visited)
    })
    return arrayClone as unknown as T
  }

  // Handle TypedArrays
  if (ArrayBuffer.isView(obj) && !(obj instanceof DataView)) {
    // Get the constructor to create a new instance of the same type
    const TypedArrayConstructor = Object.getPrototypeOf(obj).constructor
    const clone = new TypedArrayConstructor(
      (obj as unknown as TypedArray).length,
    ) as unknown as TypedArray
    visited.set(obj as object, clone)

    // Copy the values
    for (let i = 0; i < (obj as unknown as TypedArray).length; i++) {
      clone[i] = (obj as unknown as TypedArray)[i]!
    }

    return clone as unknown as T
  }

  if (obj instanceof Map) {
    const clone = new Map() as Map<unknown, unknown>
    visited.set(obj as object, clone)
    obj.forEach((value, key) => {
      clone.set(key, deepClone(value, visited))