# Serializing types to and from JSON

The SDK provides two helper functions to serialize and deserialize the
data to and from JSON while retaining the type information.

- `types.reviver`: Function to be passed to `JSON.parse`
- `types.replacer`: Function to be passed to `JSON.stringify`

Serializing the data to JSON may be necessary if you are saving the
data to
[LocalStorage](https://developer.mozilla.org/en-US/docs/Web/API/Storage/LocalStorage)
or if you have a server that fetches the data and you want to pass the
preloaded state to your [Redux
store](https://redux.js.org/recipes/server-rendering#inject-initial-component-html-and-state).

**Example:**

```js
const { reviver, replacer, UUID } = require('sharetribe-flex-sdk').types;

const testData = {
  id: new UUID('f989541d-7e96-4c8a-b550-dff1eef25815')
};

const roundtrip = JSON.parse(JSON.stringify(testData, replacer), reviver);

assert(roundtrip.id.constructor.name === 'UUID');
```

**Please note:** [Your own types](./your-own-types.md) are not serialized.

**Please note:** When an API call fails, [the error
response](./calling-the-api.md#error-response) is wrapped in
[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)
object. Stringifying an Error object may result in unexpected results. Because of
this, it's recommended that you do not stringify whole SDK responses as is, but
instead pick the `status`, `statusText` and `data` fields from the response, and
store and stringify those.