next.config.js

const path = require("path");

// https://github.com/leerob/leerob.io/blob/9adc510cbfb3da88c3b0ad15632eb876ca91b607/next.config.js#L39-L49
const csp = `
  default-src 'self';
  script-src 'self' 'unsafe-eval' 'unsafe-inline';
  style-src 'self' 'unsafe-inline' fonts.googleapis.com;
  img-src * blob: data:;
  media-src 'none';
  connect-src *;
  font-src 'self' fonts.gstatic.com;
`;

/**
 * @link https://nextjs.org/docs/api-reference/next.config.js/introduction
 * @type {import('next/dist/next-server/server/config').NextConfig}
 */
module.exports = {
  excludeDefaultMomentLocales: true,

  // https://nextjs.org/docs/api-reference/next.config.js/disabling-x-powered-by
  poweredByHeader: false,

  // https://nextjs.org/docs/api-reference/next.config.js/react-strict-mode
  reactStrictMode: true,

  // https://github.com/vercel/next.js/blob/canary/packages/next/next-server/server/config-shared.ts#L42-L65
  // experimental: {
  //   conformance: true,
  //   optimizeCss: true,
  //   optimizeImages: true,
  //   scrollRestoration: true,
  //   workerThreads: true,
  // },

  // https://nextjs.org/docs/api-reference/next.config.js/headers
  // https://github.com/leerob/leerob.io/blob/9adc510cbfb3da88c3b0ad15632eb876ca91b607/next.config.js#L51-L88
  async headers() {
    return [
      {
        source: "/(.*)",
        headers: [
          // https://vercel.com/support/articles/how-to-enable-cors#enabling-cors-in-a-next.js-app
          {
            key: "Access-Control-Allow-Credentials",
            value: "true",
          },
          {
            key: "Access-Control-Allow-Origin",
            value: "*",
          },
          {
            key: "Access-Control-Allow-Methods",
            value: "GET,OPTIONS,PATCH,DELETE,POST,PUT",
          },
          {
            key: "Access-Control-Allow-Headers",
            value: `X-CSRF-Token, X-Requested-With, Accept, Accept-Version, Content-Length, Content-MD5, Content-Type, Date, X-Api-Version`,
          },

          // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control
          {
            key: "Cache-Control",
            value: "public, s-maxage=1, stale-while-revalidate=59",
          },

          // https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP
          {
            key: "Content-Security-Policy",
            value: csp.replace(/\n/g, ""),
          },

          // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Feature-Policy
          // Opt-out of Google FLoC: https://amifloced.org/
          {
            key: "Permissions-Policy",
            value:
              "camera=(), microphone=(), geolocation=(), interest-cohort=()",
          },

          // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Referrer-Policy
          {
            key: "Referrer-Policy",
            value: "origin-when-cross-origin",
          },

          // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Strict-Transport-Security
          {
            key: "Strict-Transport-Security",
            value: "max-age=31536000; includeSubDomains; preload",
          },

          // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Frame-Options
          {
            key: "X-Frame-Options",
            value: "DENY",
          },

          // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Content-Type-Options
          {
            key: "X-Content-Type-Options",
            value: "nosniff",
          },

          // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-DNS-Prefetch-Control
          {
            key: "X-DNS-Prefetch-Control",
            value: "on",
          },
        ],
      },
    ];
  },

  // https://nextjs.org/docs/basic-features/image-optimization#domains
  images: {
    domains: ["www.datocms-assets.com"],
  },

  // https://nextjs.org/docs/api-reference/next.config.js/redirects
  async redirects() {
    return [
      // {
      //   source: "/blog/:path*",
      //   destination: "/blog",
      //   permanent: false,
      // },
    ];
  },

  // https://nextjs.org/docs/api-reference/next.config.js/custom-webpack-config
  /**
   * @param {import("webpack").Configuration} config
   * @param {{dev:boolean;isServer:boolean}} opts
   */
  webpack(config, { defaultLoaders, dev, isServer, webpack }) {
    config.plugins.push(new webpack.DefinePlugin({ __DEV__: dev }));

    return config;
  },
};