Sharing objects between custom server and Remix code (aka. Use socket.io in Remix) https://github.com/remix-run/remix/discussions/7454#discussioncomment-7498534

README.md

Main content -> remix-run/remix#7454 (comment)

requireCommon.server.ts

import debug from "~/server/debug";

const d = debug(false)!;

/**
 * Dynamically require some module. This can be useful to import a module which is initialized in the server entrypoint
 * and you want to import and access it from remix routes. Otherwise, with static imports, Remix would bundle all modules
 * and local variables of module won't be shared
 *
 * One caveat is that we cannot use this in routes directly, otherwise the route will not be defined correctly
 */
const requireCommon = (moduleName: string) => {
  let module;
  if (__dirname.endsWith("/dist")) {
    // This is /dist/index.js that imports something under app directory.
    // Remix (which uses rollup?) keeps require() as it is in index.js and places the module to under dist/app/..., so we point to the built module here.
    module = moduleName.replace("~/", "./app/");
    d(
      `import ${module} from server bundle at ${__dirname} (originally requiring ${moduleName})`
    );
  } else if (__dirname.endsWith("/sockets")) {
    // Imported from other files under sockets
    module = moduleName.replace("~/sockets/", "./");
    d(
      `import ${module} from sockets at ${__dirname} (originally requiring ${moduleName})`
    );
  } else {
    // Imported from Remix bundle
    module = moduleName.replace("~/", "../dist/app/");
    d(
      `import ${module} from remix bundle at ${__dirname} (originally requiring ${moduleName})`
    );
  }
  return require(module);
};
export default requireCommon;