# Migrate to v4.0.X

This guide assists developers in migrating from Flagship 3.X to Flagship 4.X.

The primary changes include:

* Visitor Creation options
* Flagship configuration
* Flagship SDK Status

For more details, see the [change log](https://github.com/flagship-io/flagship-ts-sdk/releases)

## Visitor Creation options

In version 4.X, when creating a visitor, the [hasConsented](/server-side/sdks/js-sdk/archived-versions/archived-js-v40x/archived-js-v40x-reference.md#hasconsented-property) option is now required. In contrast, this option was optional in version 3.X. Additionally, the `isNewInstance` option has been replaced with [shouldSaveInstance](/server-side/sdks/js-sdk/archived-versions/archived-js-v40x/archived-js-v40x-reference.md#newvisitor-method).

Below is an example of how consent is used in versions 4.X and 3.X

```typescript
const fsVisitor = Flagship.newVisitor({
  hasConsented: true, // This is now mandatory
});
```

```typescript
const fsVisitor = Flagship.newVisitor();
```

## Flagship configuration

In version 4.X, the `enableClientCache`option of [IFlagshipConfig](/server-side/sdks/js-sdk/archived-versions/archived-js-v40x/archived-js-v40x-reference.md#sdk-configuration) has been replaced with [reuseVisitorIds](/server-side/sdks/js-sdk/archived-versions/archived-js-v40x/archived-js-v40x-reference.md#sdk-configuration) and the `statusChangedCallback` has been replaced with [`onSdkStatusChanged`](/server-side/sdks/js-sdk/archived-versions/archived-js-v40x/archived-js-v40x-reference.md#sdk-configuration).

## Flagship SDK Status

The `FlagshipStatus` enum has been superseded by [`FSSdkStatus`](doc:javascript-reference#fssdkstatus).

The table below matches the `FlagshipStatus` enum keys from version 3.X to the corresponding [`FSSdkStatus`](/server-side/sdks/js-sdk/archived-versions/archived-js-v40x/archived-js-v40x-reference.md#fssdkstatus) keys in version 4.X.

| V4.X                  | V3.X             |
| --------------------- | ---------------- |
| SDK\_NOT\_INITIALIZED | NOT\_READY       |
| SDK\_NOT\_INITIALIZED | NOT\_INITIALIZED |
| SDK\_INITIALIZING     | STARTING         |
| SDK\_INITIALIZING     | POLLING          |
| SDK\_PANIC            | READY\_PANIC\_ON |
| SDK\_INITIALIZED      | READY            |

## `GetFlag` method update

In version 4.X, the approach to setting a flag's default value has been modified. The default value is no longer set using the [getFlag](/server-side/sdks/js-sdk/archived-versions/archived-js-v40x/archived-js-v40x-reference.md#getflag-method) method of visitor instance. Instead, it is now set using the [getValue](/server-side/sdks/js-sdk/archived-versions/archived-js-v40x/archived-js-v40x-reference.md#getflag-method) of [flag](/server-side/sdks/js-sdk/archived-versions/archived-js-v40x/archived-js-v40x-reference.md#ifsflag-interface) instance.

Here's how you can retrieve the default value of a flag in versions 4.X and 3.X:

```typescript

...

const flag = fsVisitor.getFlag("myFlagKey");
const flagValue = flag.getValue("default-value");
```

```typescript

...

const flag = fsVisitor.getFlag("myFlagKey", "default-value");
const flagValue = flag.getValue();
```


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