Why in the template "node-custom-server" there is server.js and server/app.ts? What can I put in the app.ts if I use SSR?

[nikas-belogolov]

From what I understood from the vite config, this server/app.ts file relates to SSR:

export default defineConfig(({ isSsrBuild }) => ({
  build: {
    rollupOptions: isSsrBuild
      ? {
          input: "./server/app.ts",
        }
      : undefined,
  }
}));

But why is this file needed and can other things be put into it or is it just for internal react-router use? When I used remix.js there was only a server.js file.

[brookslybrand]

I believe it's there just to separate the concerns of the React Router request handler from the rest of the express app. You should be able to inline it in server.js directly if you'd like