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How to Add a Progress Bar on Page Load to Next.js

Apr 16, 2021 2 min read

A very popular module for adding progress bars to JavaScript applications is NProgress.

We can easily add a progress bar on page loads by adding listeners to Next’s router routeChangeStart and routeChangeComplete events.

First off, we have to install this package.

npm install --save nprogress

Then, we can use nprogress and attach it to our router events.

// _app.jsx
import NProgress from "nprogress";
import { useEffect } from "react";
import Router from "next/router";

const App = ({ Component, pageProps }) => {
  useEffect(() => {
    Router.events.on("routeChangeStart", () => NProgress.start());
    Router.events.on("routeChangeComplete", () => NProgress.done());
    Router.events.on("routeChangeError", () => NProgress.done());
  }, []);
  return <Component {...pageProps} />;
};

But we don’t always want the progress bar to show up. It might get annoying for users, especially for pages rendered on the client-side.

We can delay the progress bar and only show it when the page load takes longer than half a second (500ms).

This can be done using setTimeout() and clearTimeout().

// _app.jsx
import NProgress from "nprogress";
import { useEffect } from "react";
import Router from "next/router";

const App = ({ Component, pageProps }) => {
  useEffect(() => {
    const delay = 500; // in milliseconds
    let timer;
    const load = () => {
      timer = setTimeout(function () {
        NProgress.start();
      }, delay);
    };
    const stop = () => {
      clearTimeout(timer);
      NProgress.done();
    };
    Router.events.on("routeChangeStart", () => load());
    Router.events.on("routeChangeComplete", () => stop());
    Router.events.on("routeChangeError", () => stop());
  }, []);
  return <Component {...pageProps} />;
};

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