How to set up analytics in React

Product analytics enables you to gather and analyze data about how users interact with your React app. To show you how to set up analytics, in this tutorial we create a basic React app with Vite, add PostHog, and use it to capture pageviews and custom events.

Creating a React app with Vite

To demonstrate the basics of PostHog analytics, we'll create a simple app with two pages and a link to navigate between them.

First, ensure Node.js is installed (version 18.0 or newer). Then create a new React app with Vite:

npm create vite@latest react-analytics -- --template react
cd react-analytics
npm install

Next, create two new files HomePage.jsx and AboutPage.jsx in your src directory:

cd ./src
touch HomePage.jsx
touch AboutPage.jsx

In HomePage.jsx, add the following code:

function HomePage() {
  return <h1>Home Page</h1>;
}

export default HomePage;

In AboutPage.jsx, add the following code:

function AboutPage() {
  return <h1>About Page</h1>;
}

export default AboutPage;

Next, we set up the routing. First, install React Router in your project:

npm install react-router-dom

Then, set up the router by replacing the code in App.jsx with the following:

import React from 'react';
import { BrowserRouter as Router, Route, Link, Routes } from 'react-router-dom';
import HomePage from './HomePage';
import AboutPage from './AboutPage'; 

function App() {
  return (
    <Router>
      <div>
        <nav>
          <ul>
            <li>
              <Link to="/">Home</Link>
            </li>
            <li>
              <Link to="/about">About</Link>
            </li>
          </ul>
        </nav>

        <Routes> 
          <Route path="/about" element={<AboutPage />} />
          <Route path="/" element={<HomePage />} />
        </Routes>
      </div>
    </Router>
  );
}

export default App;

The basic setup is now complete. Run npm run dev to see your app in action.

Adding PostHog

With our app set up, it's time to install and set up PostHog. If you don't have a PostHog instance, you can sign up for free.

First install posthog-js:

npm install posthog-js

Next, import PostHog into src/main.jsx and set up it up using your project API key and host from your project settings. Then we wrap our app with PostHogProvider to access PostHog in any component.

import React from 'react'
import ReactDOM from 'react-dom/client'
import './index.css'
import App from './App.jsx'
import posthog from 'posthog-js'
import { PostHogProvider } from 'posthog-js/react'

posthog.init('<ph_project_api_key>', {
  api_host: 'https://us.i.posthog.com',
})

ReactDOM.createRoot(document.getElementById('root')).render(
  <React.StrictMode>
    <PostHogProvider client={posthog}>
      <App />
    </PostHogProvider>
  </React.StrictMode>,
)

Once you've done this, reload your app and click the links a few times. You should see events appearing in PostHog's activity tab.

Capturing pageviews

You might notice that moving between pages only captures a single pageview event. This is because PostHog only captures pageview events when a page load is fired. Since React creates a single-page app, this only happens once and the React router handles subsequent page changes.

If we want to capture every route change, we must write code to capture pageviews that integrates with the router.

To do this, we create a new component PostHogPageviewTracker. This component combines useLocation with useEffect to capture a pageview whenever the location changes.

First, create a PostHogPageviewTracker.jsx file in your src directory. Then add the following code to it:

import { useEffect } from 'react';
import { useLocation } from 'react-router-dom';
import { usePostHog } from 'posthog-js/react'

const PostHogPageviewTracker = () => {
  const location = useLocation();
  const posthog = usePostHog()
  useEffect(() => {
    if (posthog) {
      posthog.capture('$pageview')
    }
  }, [location, posthog])

  return null;
};

export default PostHogPageviewTracker;

Then include this new component in your Router in App.jsx:

// your existing imports
import PostHogPageviewTracker from './PostHogPageviewTracker';

function App() {
  return (
    <Router>
      <PostHogPageviewTracker/>
      {/* rest of your components */}
    </Router>
  );
}

export default App;

Now, every time a user moves between pages, PostHog captures a $pageview event, not just on the first page load.

Lastly, go back to src/main.jsx and make sure to set capture_pageview in the PostHog initialization config to false. This turns off autocaptured pageviews and ensures you won't double-capture pageviews on the first load.

// your existing imports

posthog.init('<ph_project_api_key>', {
  api_host: 'https://us.i.posthog.com',
  capture_pageview: false,
})

// rest of your code

Capturing pageleaves (optional)

Once you disable automatic $pageview captures when calling posthog.init, you'll be disabling automatic $pageleave capture as well. If you want to continue capturing $pageleaves automatically, you can re-enable it.

// your existing imports

posthog.init('<ph_project_api_key>', {
  api_host: 'https://us.i.posthog.com',
  capture_pageview: false,
  capture_pageleave: true, // Opt back in because disabling $pageview capture disables $pageleave events
})

// rest of your code

Capturing custom events

Beyond pageviews, there might be more events you want to capture. To do this, you can capture custom events with PostHog.

To showcase this, update the code in HomePage.jsx to include a button that uses PostHog to capture a home_button_clicked event:

import { usePostHog } from 'posthog-js/react'

function HomePage() {
  const posthog = usePostHog()
  return (
    <div>
      <h1>Home Page</h1>
      <button 
        onClick={() => {
          posthog.capture('home_button_clicked', {
            'user_name': 'Max the Hedgehog' 
          });
      }}>
        Click Me
      </button>
    </div>
  );
}

export default HomePage;

Now when you click the button, PostHog captures the custom home_button_clicked event. Notice that we also added a property user_name to the event. This is helpful for filtering events in PostHog.

Further reading

• How to set up surveys in React
• How to set up A/B tests in React
• How to set up feature flags in React

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