React Feature Flags

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Overview

This page describes how to instrument your React application with the Datadog Feature Flags SDK. Datadog feature flags provide a unified way to remotely control feature availability in your app, experiment safely, and deliver new experiences with confidence.

The Datadog Feature Flags SDK for React is built on OpenFeature, an open standard for feature flag management. This guide explains how to install the SDK, configure the Datadog provider, and evaluate flags in your React components.

Installation

Install the Datadog OpenFeature provider and the OpenFeature React SDK using your preferred package manager:

    npm install @datadog/openfeature-browser @openfeature/react-sdk @openfeature/core
    yarn add @datadog/openfeature-browser @openfeature/react-sdk @openfeature/core
    pnpm add @datadog/openfeature-browser @openfeature/react-sdk @openfeature/core

    Initialize the provider

    Create a DatadogProvider instance and register it with OpenFeature. Do this as early as possible in your application, before rendering your React components.

    import { DatadogProvider } from '@datadog/openfeature-browser';

const provider = new DatadogProvider({
  applicationId: '<APPLICATION_ID>',
  clientToken: '<CLIENT_TOKEN>',
  env: '<ENV_NAME>',
});

    Set the evaluation context

    Define who or what the flag evaluation applies to using an evaluation context. The evaluation context includes user or session information used to determine which flag variations should be returned. Reference these attributes in your targeting rules to control who sees each variant.

    Set the provider along with the evaluation context:

    import { OpenFeature } from '@openfeature/react-sdk';

const evaluationContext = {
  targetingKey: 'user-123',
  user_id: '123',
  email: 'user@example.com',
  tier: 'premium',
};

OpenFeature.setProvider(provider, evaluationContext);
    The targetingKey is used as the randomization subject for percentage-based targeting. When a flag targets a percentage of subjects (for example, 50%), the targetingKey determines which "bucket" a user falls into. Users with the same targetingKey always receive the same variant for a given flag.

    Wrap your application

    Wrap your application with the OpenFeatureProvider component. This makes feature flags available to all child components through React context.

    import { OpenFeatureProvider } from '@openfeature/react-sdk';

function App() {
  return (
    <OpenFeatureProvider>
      <YourApp />
    </OpenFeatureProvider>
  );
}

    Evaluate flags

    The OpenFeature React SDK provides hooks for evaluating flags within your components. Each hook returns the flag value based on the evaluation context you configured.

    Boolean flags

    Use useBooleanFlagValue(key, defaultValue) for flags that represent on/off or true/false conditions:

    import { useBooleanFlagValue } from '@openfeature/react-sdk';

function CheckoutButton() {
  const isNewCheckoutEnabled = useBooleanFlagValue('new_checkout_button', false);

  if (isNewCheckoutEnabled) {
    return <NewCheckoutButton />;
  }

  return <LegacyCheckoutButton />;
}

    String flags

    Use useStringFlagValue(key, defaultValue) for flags that select between multiple variants or configuration strings:

    import { useStringFlagValue } from '@openfeature/react-sdk';

function ThemedComponent() {
  const theme = useStringFlagValue('ui_theme', 'light');

  switch (theme) {
    case 'dark':
      return <DarkTheme />;
    case 'light':
    default:
      return <LightTheme />;
  }
}

    Number flags

    Use useNumberFlagValue(key, defaultValue) for numeric flags such as limits, percentages, or multipliers:

    import { useNumberFlagValue } from '@openfeature/react-sdk';

function CartDisplay() {
  const maxItems = useNumberFlagValue('max_cart_items', 20);

  return <Cart maxItems={maxItems} />;
}

    Object flags

    Use useObjectFlagValue(key, defaultValue) for structured configuration data:

    import { useObjectFlagValue } from '@openfeature/react-sdk';

function Banner() {
  const config = useObjectFlagValue('promo_banner', {
    color: '#00A3FF',
    message: 'Welcome!',
  });

  return <PromoBanner color={config.color} message={config.message} />;
}

    Suspense support

    Built-in suspense support allows you to avoid displaying components with feature flags until provider initialization is complete, or when the context changes. Pass { suspend: true } in the hook options to use this functionality.

    For example:

    import { useBooleanFlag } from '@openfeature/react-sdk';
import { Suspense } from 'react';

import
function Content() {
  // Display a loading message if the component uses feature flags and the provider is not ready
  return (
    <Suspense fallback={"Loading..."}>
      <WelcomeMessage />
    </Suspense>
  );
}

function WelcomeMessage() {
  const { value: showNewMessage } = useBooleanFlag('show-new-welcome-message', false, { suspend: true });

  return (
    <>
      {showNewMessage ? (
        <p>Welcome! You're seeing the new experience.</p>
      ) : (
        <p>Welcome back!</p>
      )}
    </>
  );
}

    Flag evaluation details

    When you need more than just the flag value, use the detail hooks. These return both the evaluated value and metadata explaining the evaluation:

    • useBooleanFlagDetails(key, defaultValue)
    • useStringFlagDetails(key, defaultValue)
    • useNumberFlagDetails(key, defaultValue)
    • useObjectFlagDetails(key, defaultValue)

    For example:

    import { useStringFlagDetails } from '@openfeature/react-sdk';

function PaywallLayout() {
  const details = useStringFlagDetails('paywall_layout', 'control');

  console.log(details.value);   // Evaluated value (for example: "A", "B", or "control")
  console.log(details.variant); // Variant name, if applicable
  console.log(details.reason);  // Description of why this value was chosen

  return <Layout variant={details.value} />;
}

    Flag details help you debug evaluation behavior and understand why a user received a given value.

    Complete example

    Here’s a complete example showing how to set up and use Datadog Feature Flags in a React application:

    import { Suspense } from 'react';
import { DatadogProvider } from '@datadog/openfeature-browser';
import { OpenFeatureProvider, OpenFeature, useBooleanFlagValue } from '@openfeature/react-sdk';

// Initialize the Datadog provider
const provider = new DatadogProvider({
  applicationId: '<APPLICATION_ID>',
  clientToken: '<CLIENT_TOKEN>',
  env: '<ENV_NAME>',
});

// Set the evaluation context
const evaluationContext = {
  targetingKey: 'user-123',
  user_id: '123',
  user_role: 'admin',
};

OpenFeature.setProvider(provider, evaluationContext);

// Wrap your app with the OpenFeatureProvider and Suspense for loading state
function App() {
  return (
    <Suspense fallback={<Loading />}>
      <OpenFeatureProvider suspendUntilReady>
        <Page />
      </OpenFeatureProvider>
    </Suspense>
  );
}

// Use feature flags in your components
function Page() {
  const showNewFeature = useBooleanFlagValue('new_feature', false);

  return (
    <div>
      {showNewFeature ? <NewFeature /> : <ExistingFeature />}
    </div>
  );
}

    Update the evaluation context

    To update the evaluation context after initialization (for example, when a user logs in), use OpenFeature.setContext():

    // When a user logs in
await OpenFeature.setContext({
  targetingKey: user.id,
  user_id: user.id,
  email: user.email,
  plan: user.plan,
});

    Further reading

    Additional helpful documentation, links, and articles:

    Client-Side Feature FlagsDOCUMENTATION more more OpenFeature React SDKOPENFEATURE more more Browser MonitoringDOCUMENTATION more more