> ## Documentation Index
> Fetch the complete documentation index at: https://launchdarkly-preview.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.
# React Native SDK 9.x to 10.0 migration guide
> This topic explains the changes in the React Native SDK version 10 release and how to migrate to that version.
> For the complete documentation index, see [llms.txt](/llms.txt). For the full documentation snapshot, see [llms-full.txt](/llms-full.txt).
## Overview
This topic explains the changes in the React Native SDK version 10 release and how to migrate to that version.
**Version 10.0 includes the following breaking changes**:
* Version 10 of the React Native SDK has been rewritten in pure JavaScript and is compatible with Expo 49 and
50. It is compatible with React Native 0.72 and 0.73.
* The `LDClient` has been renamed `ReactNativeLDClient`, and several of the methods have changed. To learn more, read [Understanding changes to client initialization](#understanding-changes-to-client-initialization) and [Understanding changes to the client](#understanding-changes-to-the-client), below.
* The `LDConfig` configuration object has been renamed to `LDOptions`, and several of the configuration options have changed. To learn more, read [Understanding changes to configuration options](#understanding-changes-to-configuration-options), below.
* The `LDContext` has been updated: anonymous contexts now require a context key, which should be set to an empty string. To learn more, read [Understanding changes to contexts](#understanding-changes-to-contexts), below.
## Understanding changes to client initialization
There are several breaking changes to the client initialization.
Version 10 of the SDK provides a new `ReactNativeLDClient` class, which you can instantiate and pass to `LDProvider`.
When you instantiate the `ReactNativeLDClient` class, you must pass in your mobile key and indicate whether to collect [environment attributes](/sdk/features/environment-attributes#react-native). These are no longer set as part of the configuration.
`LDProvider` uses the React context API to store and pass data to child components through hooks. It requires the client.
In version 10 of the SDK, you do not specify a context when you initialize the client. Instead, you must provide the context in an `identify()` call, for example on application mount. End users will receive fallback values until you specify a context by calling `identify()`.
The following example shows the simplest way to create a shared instance of `ReactNativeLDClient`, and identify a context:
```ts title="Client initialization in React Native SDK v10" theme={null}
const client = new ReactNativeLDClient('example-mobile-key', AutoEnvAttributes.Enabled, options);
const context = { kind: 'user', key: 'example-user-key' }
const App = () => {
// call identify on App mount or later in some other component
useEffect(() => {
client.identify(context).catch((e: any) => console.log(e));
}, []);
return (
{/* your application code here */}
);
};
export default App;
```
```ts title="Client initialization in React Native SDK v9" theme={null}
let client = new LDClient();
let config: ld.LDConfig = {
mobileKey: 'example-mobile-key',
enableAutoEnvAttributes: true
};
let context: ld.LDContext = { key: 'example-user-key', kind: 'user' };
await client.configure(config, context);
```
The `identify()` method returns a promise that can be awaited:
```ts title="Waiting for identify() from cache or network" theme={null}
// This example waits for the context to be identified,
// either resolved from cache or the network
await client.identify(context);
```
```ts title="Waiting for identify() from network" theme={null}
// This example waits for the network and uses the cache as a fallback
client.identify(context, {waitForNetworkResults: true})
```
To learn more, read [Get started](/sdk/client-side/react/react-native#get-started) in the [React Native SDK reference](/sdk/client-side/react/react-native).
## Understanding changes to the client
There are several breaking changes to the client.
In version 10.0 of the SDK, the `LDClient` has been renamed `ReactNativeLDClient`. The following `ReactNativeLDClient` methods have changed:
* The `allFlags` method now no longer accepts any arguments and returns `LDFlagSet` directly, rather than returning a promise. If flags cannot be evaluated it returns an empty object. To learn more, read [Getting all flags](/sdk/features/all-flags#react-native).
* The `*Variation` methods now return the flag value directly, rather than returning a promise. Additionally, there are now corresponding hooks for each of the `*Variation` methods. For example, you can use the hook `useBoolVariation()` instead of `client.boolVariation()`. To learn more, read [Evaluating flags](/sdk/features/evaluating#react-native).
* The `*VariationDetail` methods now return evaluation details directly, rather than returning a promise. Additionally, there are now corresponding hooks for each of the `*Variation` methods. For example, you can use the hook `useBoolVariationDetail()` instead of `client.boolVariationDetail()`. To learn more, read [Flag evaluation reasons](/sdk/features/evaluation-reasons/client-side#react-native).
* The `flush` method now returns a promise that resolves to an object containing an error, if there is one, and a boolean result. To learn more, read [Flushing events](/sdk/features/flush#react-native).
* The `getConnectionMode` method signature has changed. It returns `ConnectionMode` directly, rather than returning a promise. To learn more, read [`getConnectionMode`](https://launchdarkly.github.io/js-core/packages/sdk/react-native/docs/classes/LDClientImpl.html#getConnectionMode).
The following new client methods have been added:
* The `getContext` method has been added. It returns the current context if `identify` has been called. To learn more, read [`getContext`](https://launchdarkly.github.io/js-core/packages/sdk/react-native/docs/classes/LDClientImpl.html#getContext).
* The `on` and `off` methods, used for registering and unregistering event listeners, have been added. The `on` method supports the following event names: `error`, `change`. To learn more, read [Subscribing to flag changes](/sdk/features/flag-changes#react-native).
* The `setConnectionMode` method has been added. It sets the SDK connection mode. To learn more, read [`setConnectionMode`](https://launchdarkly.github.io/js-core/packages/sdk/react-native/docs/classes/LDClientImpl.html#setConnectionMode).
* The `variation` and `variationDetail` methods have been added. These are untyped methods you can use to determine the variation of a feature flag. However, we recommend using strongly typed variation methods which perform type checks and handle type errors. To learn more, read [Evaluating flags](/sdk/features/evaluating#react-native) and [Flag evaluation reasons](/sdk/features/evaluation-reasons/client-side#react-native).
The following client methods have been removed:
* `configure`: Instead, use the `ReactNativeLDClient` constructor to create a new client instance. Then call `identify`.
* `getLastFailedConnection`
* `getLastFailure`
* `getLastSuccessfulConnection`
* `getVersion`
* `isInitialized`
* `isOffline`
* `registerAllFlagsListener`
* `registerCurrentConnectionModeListener`
* `registerFeatureFlagListener`
* `setOffline`
* `setOnline`
* `unregisterAllFlagsListener`
* `unregisterCurrentConnectionModeListener`
* `unregisterFeatureFlagListener`
To learn more, read the [release notes in GitHub](https://github.com/launchdarkly/js-core/releases/tag/react-native-client-sdk-v10.0.0).
## Understanding changes to configuration options
There are several breaking changes to the configuration options.
In version 10.0 of the SDK, the following configuration options have changed:
* The `LDConfig` object is now called `LDOptions`. To learn more, read [Configuration](/sdk/features/config#react-native).
* The `application` option is now called `applicationInfo`. If you have enabled the collection of [environment attributes](/sdk/features/environment-attributes#react-native), the `ld_application` context will only be returned if you set `applicationInfo`. To learn more, read [Application metadata configuration](/sdk/features/app-config#react-native).
* The `debugMode` option is now called `debug`.
* The `diagnosticRecordingInterval` is now specified in seconds, not milliseconds.
* The `evaluationReasons` option is now called `withReasons`. To learn more, read [Flag evaluation reasons](/sdk/features/evaluation-reasons/client-side#react-native).
* The `eventsCapacity` is now called `capacity`.
* The `flushInterval` is now specified in seconds, not milliseconds and defaults to 2 seconds.
* The `streamUrl`, `pollUrl`, and `eventsUrl` configuration options are now called `streamUri`, `baseUri`, and `eventsUri`, respectively. To learn more, read [Service endpoint configuration](/sdk/features/service-endpoint-configuration/client-side#react-native).
In version 10.0 of the SDK, the following configuration options have been added:
* `initialConnectionMode`: Sets the mode to use for connections when the SDK is initialized. To learn more, read [`initialConnectionMode`](https://launchdarkly.github.io/js-core/packages/sdk/react-native/docs/interfaces/LDOptions.html#initialConnectionMode).
* `logger`: This is an object that will perform logging for the client. In the default configuration, the SDK sends output to the console, with a default log level of `info`. To learn more, read [Logging](/sdk/features/logging#react-native).
* `sendEvents`: Whether to send analytics events back to LaunchDarkly. By default, this is true.
* `streamInitialReconnectDelay`: Sets the initial reconnect delay for the streaming connection, in seconds. The default value is
1. To learn more, read [`streamInitialReconnectDelay`](https://launchdarkly.github.io/js-core/packages/sdk/react-native/docs/interfaces/LDOptions.html#streamInitialReconnectDelay).
In version 10.0 of the SDK, the following configuration options have been removed:
* `backgroundPollingInterval`
* `connectionTimeout`
* `disableBackgroundUpdating`
* `enableAutoEnvAttributes`: Specify this as the second argument when constructing the client.
* `maxCachedContexts`
* `mobileKey`: In version 10, you pass the mobile key in during client initialization. You can no longer set it as a configuration option. To learn more, read [Understanding changes to client initialization](#understanding-changes-to-client-initialization), above.
* `offline`: Use `setConnectionMode`.
* `pollingInterval`
* `pollUrl`
* `secondaryMobileKeys`
* `stream`
* `useReport`
To learn more, read the [release notes in GitHub](https://github.com/launchdarkly/js-core/releases/tag/react-native-client-sdk-v10.0.0).
## Understanding changes to contexts
In version 10 of the SDK, you must include the `key` attribute when building the context.
If the context is anonymous, you should set the `key` to an empty string. The SDK will automatically set the key to a LaunchDarkly-specific, device-unique string that is consistent between app restarts and device reboots.
The SDK gives a usage error if you omit the `key` attribute. It also gives a usage error if you set the key to an empty string and do not mark the context as anonymous.
Here's how:
```js title="React Native SDK v10" theme={null}
// This device context is anonymous
const deviceContext = {
// The key attribute is required and should be empty
// The SDK will automatically generate a unique, stable key
key: '',
kind: 'device',
deviceId: '12345',
anonymous: true
}
```
In versions 7 through 9 of the SDK, you could omit the context key when building an anonymous context, and the client would automatically set it to a LaunchDarkly-specific, device-unique string that is consistent between app restarts and device reboots.
To learn more, read [Anonymous contexts and users](/sdk/features/anonymous#react-native).