Function loadFromStorage

packages/db/src/local-storage.ts:632–679

* Load data from storage and return as a Map * @param parser - The parser to use for deserializing the data * @param storageKey - The key used to store data in the storage API * @param storage - The storage API to load from (localStorage, sessionStorage, etc.) * @returns Map of stored items with

(
  storageKey: string,
  storage: StorageApi,
  parser: Parser,
)

 * @returns Map of stored items with version tracking, or empty Map if loading fails
 */
function loadFromStorage<T extends object>(
  storageKey: string,
  storage: StorageApi,
  parser: Parser,
): Map<string | number, StoredItem<T>> {
  try {
    const rawData = storage.getItem(storageKey)
    if (!rawData) {
      return new Map()
    }

    const parsed = parser.parse(rawData)
    const dataMap = new Map<string | number, StoredItem<T>>()

    // Handle object format where keys map to StoredItem values
    if (
      typeof parsed === `object` &&
      parsed !== null &&
      !Array.isArray(parsed)
    ) {
      Object.entries(parsed).forEach(([encodedKey, value]) => {
        // Runtime check to ensure the value has the expected StoredItem structure
        if (
          value &&
          typeof value === `object` &&
          `versionKey` in value &&
          `data` in value
        ) {
          const storedItem = value as StoredItem<T>
          const decodedKey = decodeStorageKey(encodedKey)
          dataMap.set(decodedKey, storedItem)
        } else {
          throw new InvalidStorageDataFormatError(storageKey, encodedKey)
        }
      })
    } else {
      throw new InvalidStorageObjectFormatError(storageKey)
    }

    return dataMap
  } catch (error) {
    console.warn(
      `[LocalStorageCollection] Error loading data from storage key "${storageKey}":`,
      error,
    )
    return new Map()
  }
}

/**
 * Internal function to create localStorage sync configuration