google analytics nextjs

export const GA_TRACKING_ID = "<INSERT_TAG_ID>";

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

type GTagEvent = {
  action: string;
  category: string;
  label: string;
  value: number;
};

// https://developers.google.com/analytics/devguides/collection/gtagjs/events
export const event = ({ action, category, label, value }: GTagEvent): void => {
  window.gtag("event", action, {
    event_category: category,
    event_label: label,
    value,
  });
};
npm i -D @types/gtag.js
import { AppProps } from "next/app";
import { useRouter } from "next/router";
import { useEffect } from "react";
import * as gtag from "../lib/gtag";
const isProduction = process.env.NODE_ENV === "production";

const App = ({ Component, pageProps }: AppProps): JSX.Element => {
  const router = useRouter();

  useEffect(() => {
    const handleRouteChange = (url: URL) => {
      /* invoke analytics function only for production */
      if (isProduction) gtag.pageview(url);
    };
    router.events.on("routeChangeComplete", handleRouteChange);
    return () => {
      router.events.off("routeChangeComplete", handleRouteChange);
    };
  }, [router.events]);
  // eslint-disable-next-line react/jsx-props-no-spreading
  return <Component {...pageProps} />;
};

export default App;