Launch Darkly React Native Client Factory

This is an ergonomic wrapper around the launchdarkly-react-native-client sdk package.

It makes using launch darkly feature flags in your React Native components this easy:

const MyComponent = () => {
  const myFF = useFeatureFlag('my-feature-flag')
  //...
}

The feature flags returned by this hook are strongly typed (if you're using typescript), and update and rerender your component dynamically.

installation

This package assumes that it will be used in a React Native application.

If you don't already have it, you will need the the launchdarkly-react-native-client sdk

npm i launchdarkly-react-native-client

and, of course

npm i launch-darkly-react-native-client-factory

usage

This factory will create a context provider, hooks and some escape hatch functions that you will need to re-export for use in your application.

Create a file called LaunchDarkly.ts and put this in it

// LaunchDarkly.ts
import { LaunchDarklyReactNativeFactory } from 'launch-darly-react-native-client-factory'

export const {
  LaunchDarklyProvider,
  useFeatureFlag,
  useAllFeatureFlags,
  getGlobalLdClient,
  getFeatureFlag,
} = LaunchDarklyReactNativeClientFactory({
  // **************************************************************
  // ! any feature flags that your app uses must be declared here !
  // ***************************************************************
  'example-boolean-feature-flag': { type: Boolean, defaultVal: false },
  'example-number-feature-flag': { type: Number, defaultVal: 123 },
  'example-string-feature-flag': { type: String, defaultVal: 'asdf' },
  'example-json-feature-flag': { type: Object, defaultVal: {} },
})

// Note: You may also define context and config asynchronously via hooks with their initial value as undefined.
// If you do this then the launch darkly client won't be initialized until context and config are.
// Your app will render with all feature flags set to their defaults until everything is ready to go.
export const context = {
  // learn how to create your launch darkly context and config here
  // https://docs.launchdarkly.com/sdk/client-side/react/react-native
}
export const config = {
  // learn how to create your launch darkly context and config here
  // https://docs.launchdarkly.com/sdk/client-side/react/react-native
}

You will need to add the provider to your app.tsx like this:

// App.tsx
import React from 'react';
import { LaunchDarklyProvider, context, config } from './LaunchDarkly';

export const app () => {
  return (
    <LaunchDarklyProvider context={context} config={config}>
      <TheRestOfYourAppGoesHere />
    </LaunchDarklyProvider>
  );
}

now, in your react native component, use it like this:

// ExampleComponent.tsx
import React from 'react'
import { useFeatureFlag } from './LaunchDarkly'
import { Text } from 'react-native'

export const ExampleComponent = () => {
  const darklyText = useFeatureFlag('example-string-feature-flag')
  const enableFancyFeature = useFeatureFlag('example-boolean-feature-flag')
  return (
    <>
      <Text>Example component</Text>
      <Text>{DarklyText}</Text>
      {enableFancyFeature && <Text>Fancy Feature Enabled!</Text>}
    </>
  )
}

This library has a few other features (such as overriding a flag's default value). You will find it (mostly) documented in the jsdocs comments in the codebase.