How to add Google Analytics to Next.js app

#nextjs #react

If you have started working with Next.js recently and wanted to add Google Analytics to your website, then you are at the right place!

Creating a Google Analytics tag

Now click on the Settings Icon (⚙️ Admin) at the bottom and click on Create Account
(If you already have an account, you can click on Create Property).

Now fill in the account name:

Fill in the property details along with the time zone and currency:

Finally, fill in the business details and click on Create:

Now you will be redirected to a page with the following options. Here click on Web.

In the next step provide your website details and click on Create stream.

Now you will be provided with a measurement id. Make a note of it. It will be used in the next step.

Creating a Next.js app

Now create a Next.js app, if you do not have one, using the following command:

npx create-next-app@latest next-ga-integration

Adding Google Analytics

Create a file named gtag.js with the following content (replace GA_TRACKING_ID value with yours):

export const GA_TRACKING_ID = "G-226MBLFR8V" //replace it with your measurement id

// https://developers.google.com/analytics/devguides/collection/gtagjs/pages
export const pageview = url => {
  window.gtag("config", GA_TRACKING_ID, {
    page_path: url,
  })
}

// https://developers.google.com/analytics/devguides/collection/gtagjs/events
export const event = ({ action, category, label, value }) => {
  window.gtag("event", action, {
    event_category: category,
    event_label: label,
    value: value,
  })
}

We have 2 functions here:

pageview: To track users navigating to different pages.
event: To track events like add to cart, place order, etc.

Now open _app.js and include the following code:

import "@/styles/globals.css"
import Script from "next/script"
import { useRouter } from "next/router"
import { useEffect } from "react"
import * as gtag from "gtag"

export default function App({ Component, pageProps }) {
  const router = useRouter()
  useEffect(() => {
    const handleRouteChange = url => {
      gtag.pageview(url)
    }
    router.events.on("routeChangeComplete", handleRouteChange)
    return () => {
      router.events.off("routeChangeComplete", handleRouteChange)
    }
  }, [router.events])

  return (
    <>
      <Script
        strategy="afterInteractive"
        src={`https://www.googletagmanager.com/gtag/js?id=${gtag.GA_TRACKING_ID}`}
      />
      <Script
        id="gtag-init"
        strategy="afterInteractive"
        dangerouslySetInnerHTML={{
          __html: `
            window.dataLayer = window.dataLayer || [];
            function gtag(){dataLayer.push(arguments);}
            gtag('js', new Date());
            gtag('config', '${gtag.GA_TRACKING_ID}', {
              page_path: window.location.pathname,
            });
          `,
        }}
      />
      <Component {...pageProps} />;
    </>
  )
}

In the above code:

We have included the Google Analytics script and loading it after the page becomes interactive so that it doesn't affect the page loading time.
We have a useEffect where we listen to route changes and call the pageview function, defined inside gtag.js. This is required since in Next.js, whenever routing happens, the page doesn't completely reload and Google Analytics will not be able to pick up the route change automatically.

Now your application is setup with Google Analytics and you can track the live users:

Top comments (4)

Eduard Constantin • Jul 16 '23

I think this way is safer:

<Script id="gtag-init" strategy="afterInteractive">
          {`
          window.dataLayer = window.dataLayer || [];
          function gtag(){dataLayer.push(arguments);}
          gtag('js', new Date());

          gtag('config', '${gtag.GA_TRACKING_ID}');
        `}
</Script>