# Integrate JavaScript SDK v3 with your Next.js App

This guide will help you integrate RudderStack with your Next.js app using the JavaScript SDK v3. On successful integration, you can track and send real-time user events to your preferred destinations via RudderStack.

To set up the event stream on your Next.js app, you need to perform the following steps:

Integrate JavaScript SDK with your Next.js app and set up the tracking code.
Configure a destination in RudderStack.
Deploy your Next.js app and verify the events.

Prerequisites

This guide assumes you have installed and set up your Next.js app. Refer to the Next.js documentation for more information.

Integrate JavaScript SDK with your Next.js app

Integrating the JavaScript SDK with your Next.js app involves the following steps:

Creating a JavaScript source in RudderStack.
Installing and configuring the JavaScript SDK in your Next.js app.

Create a JavaScript source

The RudderStack JavaScript source is required track the events from your Next.js app. Follow these steps to set it up in your RudderStack dashboard:

Note the data plane URL in your RudderStack dashboard. This is required to set up the JavaScript SDK in your Next.js app.

Click the Sources button in the left navigation bar and select New Source to create a source. Under Sources, select Event Streams > JavaScript.
Assign a name to your source and click Continue.
Your JavaScript source is now configured. Note down the write key for this source:

Install and configure the SDK in your app

You can integrate RudderStack with your Next.js app and set up the tracking code by following the steps below:

In your Next.js project folder, create a useRudderAnalytics.ts file with the following code:

javascript

import { useEffect, useState } from 'react';
import type { RudderAnalytics } from '@rudderstack/analytics-js';

const useRudderStackAnalytics = (): RudderAnalytics | undefined => {
  const [analytics, setAnalytics] = useState<RudderAnalytics>();

  useEffect(() => {
    if (!analytics) {
      const initialize = async () => {
        const { RudderAnalytics } = await import('@rudderstack/analytics-js');
        const analyticsInstance = new RudderAnalytics();

        analyticsInstance.load('WRITE_KEY', 'DATA_PLANE_URL');

        analyticsInstance.ready(() => {
          console.log('We are all set!!!');
        });
        
        setAnalytics(analyticsInstance);
      };

      initialize().catch(e => console.log(e));
    }
  }, [analytics]);

  return analytics;
};

export default useRudderStackAnalytics;

Replace WRITE_KEY and DATA_PLANE_URL with your JavaScript source write key and the data plane URL obtained in the Creating a JavaScript source in RudderStack section above.
To buffer the events triggered before the SDK is loaded, add the following script in the layout.tsx file within the src folder:

javascript

import Script from 'next/script';

export default function RootLayout({ children }: { children: React.ReactNode }) {
  return (
    <html lang='en'>
      <head>
        <Script id='bufferEvents'>
          {`
            window.rudderanalytics = [];
            var methods = [
              'setDefaultInstanceKey',
              'load',
              'ready',
              'page',
              'track',
              'identify',
              'alias',
              'group',
              'reset',
              'setAnonymousId',
              'startSession',
              'endSession',
              'consent'
            ];
            for (var i = 0; i < methods.length; i++) {
              var method = methods[i];
              window.rudderanalytics[method] = (function (methodName) {
                return function () {
                  window.rudderanalytics.push([methodName].concat(Array.prototype.slice.call(arguments)));
                };
              })(method);
            }
            // Below line is only for demonstration purpose, SPA code is better place for auto page call
            window.rudderanalytics.page('sample page call');
        `}
        </Script>
      </head>
      <body className={inter.className}>{children}</body>
    </html>
  );
}

If you are using an app router, go to the app folder and open the page.tsx file. If you are using a page router, go to the pages folder and open the index.tsx file. Then, add the following code:

javascript

import { useEffect } from "react";
import useRudderStackAnalytics from './useRudderAnalytics';

export default function Home() {
  const analytics = useRudderStackAnalytics();

  const page = () => {
    analytics?.page('Cart Viewed');
  };
  const identify = () => {
    analytics?.identify('sample-user-123');
  };
  const track = () => {
    analytics?.track('Order Completed');
  };

  useEffect(() => {
    if(analytics) {
      analytics.page('Auto track');
    }
  }, [analytics])

return (
    <main className='flex min-h-screen flex-col items-center justify-between p-24'>
      <div className='mb-32 grid text-center lg:max-w-5xl lg:w-full lg:mb-0 lg:grid-cols-4 lg:text-left'>
        <button
          onClick={page}
          className='group rounded-lg border border-transparent px-5 py-4 transition-colors hover:border-gray-300 hover:bg-gray-100 hover:dark:border-neutral-700 hover:dark:bg-neutral-800/30'>
          <h2 className={`mb-3 text-2xl font-semibold`}>Page </h2>
          <p className={`m-0 max-w-[30ch] text-sm opacity-50`}>
            Clicking this tile will trigger a page event.
          </p>
        </button>
     </div>
	</main>
 );
}

See the sample Next.js app for more information.

Configure a destination in RudderStack

This section details the steps required to set up a destination in RudderStack, where you can send all events tracked by the JavaScript SDK you set up above.

In your RudderStack dashboard, click Destinations > New destination.
Choose your preferred destination from the list.
Assign a name to the destination and click Continue.
Select the JavaScript source configured in the above section and click Continue.
Configure the destination with the required settings.

Optionally, you can add a user transformation to this destination to transform your events.

Deploy your app and verify events

To verify if your event stream is working correctly, deploy your Next.js app and test if the events are tracked and delivered correctly. To do so, follow these steps:

From your terminal, navigate to the folder containing your Next.js app and run following command:

bash

npm run dev

Open the local server URL(generally http://localhost:3000/) in your browser to view the app.
Go to your browser’s developer tools and open the Network tab. Click the buttons in your app to trigger the RudderStack events.
Verify in the Network tab if the events are sent successfully:

Go to the Live Events tab of your JavaScript source in the RudderStack dashboard to check if the events are tracked. Note that you may face a minor delay before the events start showing up in your dashboard.
Go to your destination to verify if the events are received successfully.