To what extent was the task completed correctly, what should be corrected?

Question

JavaScript

There was a task to process "GET", "POST", "DELETE" requests.
Wrote. It seems like everything even works. But it is clear that there are 100,500 shortcomings.
Can you please tell me what should be added / corrected in the code?
curl http://localhost:8080/page/index.html

curl -X DELETE http://localhost:8080/page/index.html

curl -d "Hello world" http://localhost:8080/page/index.html

// app.js

let http = require("http");
let fs = require("fs");
let handler = require("./handler");

new http.createServer(handler).listen(8080);

// handler.js

let url = require("url");
let fs = require("fs");
let config = require("config");
let path = require("path");

module.exports = (req, res) => {
  let urlParsed = url.parse(req.url);
  let pathname = urlParsed.pathname;
  let filePath = path.join(config.publicRoot, pathname);

  if (!filePath.startsWith(config.publicRoot + path.sep)) {
    res.statusCode = 400;

    res.end("Bye bye silly hacker!");
  }

  fs.readFile(filePath, (err, content) => {
    if (err) {
      if (err.code == "ENOENT") {
        res.statusCode = 404;

        res.end("404");
      } else {
        res.statusCode = 500;

        res.end("Server Error")
      }
    }

    if (req.method == "GET") {
      let file = new fs.ReadStream(filePath);

      file.pipe(res);

      file.on("error", err => {
        res.statusCode = 500;
        res.end("Server error");

        console.error(err);
      });

      res.on("close", () => {
        file.destroy();
      });
    }

    if (req.method == "POST") {
      let file = new fs.createWriteStream(filePath);

      req.pipe(file);

      res.end();
    }

    if (req.method == "DELETE") {
      try {
        fs.unlink(filePath, err => {
          if (err) {
            throw err;
          }

          res.statusCode = 200;

          res.end("File was removed");
        });
      } catch (err) {
        if (err.code == "ENOENT") {
          res.statusCode = 404;

          res.end("File not found");
        } else {
          res.statusCode = 500;

          res.end("Error on removing file");
        }
      }
    }
  });
};

// config.js

let path = require("path");

module.exports = {
  projectRoot: process.cwd(),
  publicRoot: process.cwd() + path.sep + "public"
};

Answer 1

Well, for starters, split it into files so that each has one handler left and add a simple router that does this.
The next step is to make the request processing as a chain of middleware, in general, according to your wording of the task, it is completely unclear what exactly they wanted from you. What kind of job is this?