React quickstart

1. Install hypertune

Once you have a React application ready, install Hypertune's JavaScript SDK:

npm

npm install hypertune

yarn

pnpm

2. Set environment variables

Define the following environment variables in your .env file:

.env

VITE_HYPERTUNE_TOKEN=token
HYPERTUNE_FRAMEWORK=react
HYPERTUNE_OUTPUT_DIRECTORY_PATH=src/generated

Replace token with your main project token which you can find in the Settings tab of your project.

3. Generate the client

Generate a type-safe client to access your flags by running:

npm

npx hypertune

yarn

pnpm

4. Use the client

Create a new <AppHypertuneProvider> component that wraps the generated <HypertuneProvider> component:

src/components/AppHypertuneProvider.tsx

import { HypertuneProvider } from '../generated/hypertune.react'

export default function AppHypertuneProvider({
  children,
}: {
  children: React.ReactNode
}) {
  return (
    <HypertuneProvider
      createSourceOptions={{
        token: import.meta.env.VITE_HYPERTUNE_TOKEN!,
      }}
      rootArgs={{
        context: {
          environment:
            process.env.NODE_ENV === 'development'
              ? 'development'
              : 'production',
          user: {
            id: 'e23cc9a8-0287-40aa-8500-6802df91e56a',
            name: 'Example User',
            email: '[email protected]',
          },
        },
      }}
    >
      {children}
    </HypertuneProvider>
  )
}

Wrap your app with the <AppHypertuneProvider> component:

src/main.tsx

import React from 'react'
import ReactDOM from 'react-dom/client'
import App from './App.tsx'
import AppHypertuneProvider from './components/AppHypertuneProvider.tsx'
import './index.css'

ReactDOM.createRoot(document.getElementById('root')!).render(
  <React.StrictMode>
    <AppHypertuneProvider>
      <App />
    </AppHypertuneProvider>
  </React.StrictMode>
)

Then use the generated useHypertune hook:

src/components/ClientComponent.tsx

import { useHypertune } from '../generated/hypertune.react'

export default function ClientComponent() {
  const hypertune = useHypertune()

  const exampleFlag = hypertune.exampleFlag({ fallback: false })

  return <div>Example Flag: {String(exampleFlag)}</div>
}

If you have a Content Security Policy, add the following to your connect-src directive: https://edge.hypertune.com https://gcp.fasthorse.workers.dev. This enables reporting of flag evaluations, experiment exposures, and analytics events.

5. (Optional) Add the Hypertune Toolbar

The Hypertune Toolbar lets you view and override feature flags directly in your frontend. Follow the guide to add it to your app.

6. (Optional) Include a build-time snapshot

If you try accessing a flag immediately after the app loads, you'll get your hardcoded fallback value if the SDK hasn't initialized from Hypertune Edge yet. This can result in layout shift or a flicker if the flag value changes when the SDK initializes.

To avoid this, you can include a snapshot of your flag logic in the generated client at build time. The SDK will instantly initialize from the snapshot first before fetching the latest flag logic from Hypertune Edge.

Add the following environment variable to your .env file:

HYPERTUNE_INCLUDE_INIT_DATA=true

Then regenerate the client.

You can keep the snapshot fresh by setting up a webhook to regenerate the client and redeploy your app on every Hypertune commit. In this case, you don't need to initialize from Hypertune Edge at all.

Next steps

Now you can update the logic for exampleFlag from the Hypertune UI without updating your code or waiting for a new build, deployment, or app release.

To add a new flag, create it in the Hypertune UI then regenerate the client.