@unleash/proxy-client-react

What is @unleash/proxy-client-react?

@unleash/proxy-client-react is a React client for the Unleash feature management system. It allows developers to easily integrate feature toggles into their React applications, enabling dynamic feature management and experimentation.

What are @unleash/proxy-client-react's main functionalities?

Initialize Unleash Client

This code initializes the Unleash client with the necessary configuration, including the URL of the Unleash API, the client key, and the application name. The `start` method is called to begin fetching feature toggles.

import { UnleashClient } from '@unleash/proxy-client-react';

const client = new UnleashClient({
  url: 'https://app.unleash-hosted.com/demo/api/',
  clientKey: 'proxy-client-key',
  appName: 'my-react-app'
});

client.start();

Use Feature Toggles in Components

This code demonstrates how to use the `useFlag` hook to check the status of a feature toggle within a React component. Depending on whether the feature toggle is enabled or disabled, different content is rendered.

import { useFlag } from '@unleash/proxy-client-react';

const MyComponent = () => {
  const isEnabled = useFlag('my-feature-toggle');

  return (
    <div>
      {isEnabled ? <p>Feature is enabled</p> : <p>Feature is disabled</p>}
    </div>
  );
};

Custom Context Provider

This code shows how to wrap your application with the `UnleashProvider` to provide the Unleash client configuration context to all components within the application. This makes it easier to use feature toggles throughout the app.

import { UnleashProvider } from '@unleash/proxy-client-react';

const App = () => (
  <UnleashProvider
    config={{
      url: 'https://app.unleash-hosted.com/demo/api/',
      clientKey: 'proxy-client-key',
      appName: 'my-react-app'
    }}
  >
    <MyComponent />
  </UnleashProvider>
);

Other packages similar to @unleash/proxy-client-react

react-feature-toggles

react-feature-toggles is a lightweight library for managing feature toggles in React applications. It provides a simple API for defining and using feature toggles, but it does not offer the same level of integration with a feature management system like Unleash.

launchdarkly-react-client-sdk

launchdarkly-react-client-sdk is the official React SDK for LaunchDarkly, a feature management platform. It offers similar functionality to @unleash/proxy-client-react, including feature flag evaluation and context management, but it is tied to the LaunchDarkly service.

react-ab-test

react-ab-test is a library for A/B testing in React applications. It allows developers to define experiments and variants, and track user interactions. While it focuses on A/B testing rather than feature toggles, it provides similar capabilities for experimentation.

README

DISCLAIMER:

This library is meant to be used with the unleash-proxy. The proxy application layer will sit between your unleash instance and your client applications, and provides performance and security benefits. DO NOT TRY to connect this library directly to the unleash instance, as the datasets follow different formats because the proxy only returns evaluated toggle information.

Installation

npm install @unleash/proxy-client-react unleash-proxy-client
// or
yarn add @unleash/proxy-client-react unleash-proxy-client

Upgrade path from v1 -> v2

If you were previously using the built in Async storage used in the unleash-proxy-client-js, this no longer comes bundled with the library. You will need to install the storage adapter for your preferred storage solution. Otherwise there are no breaking changes.

Upgrade path from v2 -> v3

Previously the unleash client was bundled as dependency directly in this library. It's now changed to a peer dependency and listed as an external.

In v2 there was only one distribution based on the fact that webpack polyfilled the necessary features in v4. This is no longer the case in webpack v5. We now provide two distribution builds, one for the server and one for the client - and use the browser field in the npm package to hint module builders about which version to use. The default dist/index.js file points to the node version, while the web build is located at dist/index.browser.js

Upgrading should be as easy as running yarn again with the new version, but we made the made bump regardless to be safe. Note: If you are not able to resolve the peer dependency on unleash-proxy-client you might need to run npm install unleash-proxy-client

Initialization

Import the provider like this in your entrypoint file (typically index.js/ts):

import { createRoot } from 'react-dom/client';
import { FlagProvider } from '@unleash/proxy-client-react';

const config = {
  url: 'https://HOSTNAME/proxy',
  clientKey: 'PROXYKEY',
  refreshInterval: 15,
  appName: 'your-app-name',
  environment: 'dev',
};

const root = createRoot(document.getElementById('root'));

root.render(
  <React.StrictMode>
    <FlagProvider config={config}>
      <App />
    </FlagProvider>
  </React.StrictMode>
);

Alternatively, you can pass your own client in to the FlagProvider:

import { createRoot } from 'react-dom/client';
import { FlagProvider, UnleashClient } from '@unleash/proxy-client-react';

const config = {
  url: 'https://HOSTNAME/proxy',
  clientKey: 'PROXYKEY',
  refreshInterval: 15,
  appName: 'your-app-name',
  environment: 'dev',
};

const client = new UnleashClient(config);
const root = createRoot(document.getElementById('root'));

root.render(
  <React.StrictMode>
    <FlagProvider unleashClient={client}>
      <App />
    </FlagProvider>
  </React.StrictMode>
);

Deferring client start

By default, the Unleash client will start polling the Proxy for toggles immediately when the FlagProvider component renders. You can delay the polling by:

• setting the startClient prop to false
• passing a client instance to the FlagProvider

root.render(
  <React.StrictMode>
    <FlagProvider unleashClient={client} startClient={false}>
      <App />
    </FlagProvider>
  </React.StrictMode>
);

Deferring the client start gives you more fine-grained control over when to start fetching the feature toggle configuration. This could be handy in cases where you need to get some other context data from the server before fetching toggles, for instance.

To start the client, use the client's start method. The below snippet of pseudocode will defer polling until the end of the asyncProcess function.

const client = new UnleashClient({ /* ... */ })

useEffect(() => {
  const asyncProcess = async () => {
	// do async work ...
	client.start()
    }
    asyncProcess()
  }, [])

return (
  // Pass client as `unleashClient` and set `startClient` to `false`
  <FlagProvider unleashClient={client} startClient={false}>
    <App />
  </FlagProvider>
)

Usage

Check feature toggle status

To check if a feature is enabled:

import { useFlag } from '@unleash/proxy-client-react';

const TestComponent = () => {
  const enabled = useFlag('travel.landing');

  if (enabled) {
    return <SomeComponent />
  }
  return <AnotherComponent />
};

export default TestComponent;

Check variants

To check variants:

import { useVariant } from '@unleash/proxy-client-react';

const TestComponent = () => {
  const variant = useVariant('travel.landing');

  if (variant.enabled && variant.name === "SomeComponent") {
    return <SomeComponent />
  } else if (variant.enabled && variant.name === "AnotherComponent") {
    return <AnotherComponent />
  }
  return <DefaultComponent />
};

export default TestComponent;

Defer rendering until flags fetched

useFlagsStatus retrieves the ready state and error events. Follow the following steps in order to delay rendering until the flags have been fetched.

import { useFlagsStatus } from '@unleash/proxy-client-react'

const MyApp = () => {
  const { flagsReady, flagsError } = useFlagsStatus();

  if (!flagsReady) {
    return <Loading />
  }
  return <MyComponent error={flagsError}/>
}

Updating context

Follow the following steps in order to update the unleash context:

import { useUnleashContext, useFlag } from '@unleash/proxy-client-react'

const MyComponent = ({ userId }) => {
  const variant = useFlag("my-toggle");
  const updateContext = useUnleashContext();

  useEffect(() => {
    // context is updated with userId
    updateContext({ userId })
  }, [userId])

  useEffect(() => {
    async function run() {
    // Can wait for the new flags to pull in from the different context
      await updateContext({ userId });
      console.log('new flags loaded for', userId);
    }
    run();
  }, [userId]);
}

Use unleash client directly

import { useUnleashContext, useUnleashClient } from '@unleash/proxy-client-react'

const MyComponent = ({ userId }) => {
  const client = useUnleashClient();

  const updateContext = useUnleashContext();

  const login = () => {
    // login user
    if (client.isEnabled("new-onboarding")) {
      // Send user to new onboarding flow
    } else (
      // send user to old onboarding flow
    )
  }

  return <LoginForm login={login}/>
}

React Native

IMPORTANT: This no longer comes included in the unleash-proxy-client-js library. You will need to install the storage adapter for your preferred storage solution.

Because React Native doesn't run in a web browser, it doesn't have access to the localStorage API. Instead, you need to tell Unleash to use your specific storage provider. The most common storage provider for React Native is AsyncStorage. To configure it, add the following property to your configuration object:

const config = {
  storageProvider: {
    save: (name, data) => AsyncStorage.setItem(name, JSON.stringify(data)),
    get: async (name) => {
      const data = await AsyncStorage.getItem(name);
      return data ? JSON.parse(data) : undefined;
    }
  },
};

Usage with class components

Since this library uses hooks you have to implement a wrapper to use with class components. Beneath you can find an example of how to use this library with class components, using a custom wrapper:

import React from "react";
import {
  useFlag,
  useUnleashClient,
  useUnleashContext,
  useVariant,
  useFlagsStatus
} from "@unleash/proxy-client-react";

interface IUnleashClassFlagProvider {
  render: (props: any) => React.ReactNode;
  flagName: string;
}

export const UnleashClassFlagProvider = ({
  render,
  flagName
}: IUnleashClassFlagProvider) => {
  const enabled = useFlag(flagName);
  const variant = useVariant(flagName);
  const client = useUnleashClient();

  const updateContext = useUnleashContext();
  const { flagsReady, flagsError } = useFlagsStatus();

  const isEnabled = () => {
    return enabled;
  };

  const getVariant = () => {
    return variant;
  };

  const getClient = () => {
    return client;
  };

  const getUnleashContextSetter = () => {
    return updateContext;
  };

  const getFlagsStatus = () => {
    return { flagsReady, flagsError };
  };

  return (
    <>
      {render({
        isEnabled,
        getVariant,
        getClient,
        getUnleashContextSetter,
        getFlagsStatus
      })}
    </>
  );
};

Wrap your components like so:

    <UnleashClassFlagProvider
      flagName="demoApp.step1"
      render={({ isEnabled, getClient }) => (
        <MyClassComponent isEnabled={isEnabled} getClient={getClient} />
      )}
    />