example.js

const { createServer } = require("http");
const fs = require("fs");
const fsp = require("fs").promises;
let path = require("path");
const { parse } = require("querystring");

/*
The querystring module provides utilities for parsing and formatting url query strings 
The parse method of the query string parses a URL query string into a collection of keys and value pairs.
For example  , the query string 'name=adeleke&[email protected]' is parsed into 
{
    name : 'adeleke' , 
    email : '[email protected]'
}
*/

const PORT = 8000;
const CACHE = {};

//For express , add the server caching in a middleware
const grabRequestBody = async (req, cb) => {
    const FORM_ENCODINGS = [
        "application/x-www-form-urlencoded",
        "multipart/form-data",
    ];
    const { headers } = req;
    if (FORM_ENCODINGS.includes(headers["content-type"])) {
        let body = "";
        req.on("data", (chunk) => {
            body += chunk.toString();
        });

        req.on("error", (error) => {
            throw new Error(error.message);
        });

        req.on("end", () => {
            cb(parse(body));
        });
    } else {
        cb(null);
    }
};

const requestListener = async (req, res) => {
    let { method, url } = req;
    if (url === "/") {
        res.writeHead(200, { "Content-Type": "text/html" });
        res.write("<h1>Welcome to Bigjara</h1>");
        res.write("<p>We are a startup focused on Internet Technologies</p>");
        res.end();
    } else if (url === "/sign-up") {
        if (method === "GET") {
            try {
                let fileContent = CACHE["signUp"];
                if (fileContent) {
                    console.log(fileContent);
                    res.writeHead(200, { "Content-Type": "text/html" });
                    res.end(fileContent);
                } else {
                    let fileName = "sign-up.html";
                    let filePath = path.join(__dirname, fileName);
                    console.log("Not from cache");
                    fileContent = await fsp.readFile(filePath);
                    CACHE["signUp"] = fileContent;
                    res.writeHead(200, { "Content-Type": "text/html" });
                    res.end(fileContent);
                }
            } catch (error) {
                res.writeHead(500, { "Content-Type": "text/html" });
                res.write(`<h1>${error.message}</h1>`);
                res.end();
            }
        } else if (method === "POST") {
            grabRequestBody(req, (result) => {
                console.log(result);
                let bodyContent = JSON.stringify(result); // Strinify the req body object
                let parseContent = JSON.parse(bodyContent);
                let { email, password, username } = parseContent;

                let newFile = fsp.appendFile("users.txt", username + "\n");
                if (newFile) console.log("New name added");
                //res.writeHead(200 , {'content-type' : 'application/json'})
                let messages = ["hi", "hello", "paul"];
                messages.map((message) => res.write(`<p>${message}</p>`));
                res.write("<h1>Registration was successful</h1>");
                res.write(
                    `<p>Hello ${username} , your email is ${email} and password is ${password}</p>`
                );

                res.end();
            });
        }
    } else if (url === "/about") {
        fs.readFile("about-bigjara.html", (err, data) => {
            if (err) {
                res.writeHead(500, { "Content-Type": "text/plain" });
                res.write("Error 500 : Internal Server Error");
                res.end();
            } else {
                res.writeHead(500, { "Content-Type": "text/html" });
                res.write(data);
                res.end();
            }
        });
    } else {
        res.statusCode = 404;
        res.setHeader("Content-Type", "text/html");
        res.write("<h1>Error 404</h1>");
        res.write("<p>Return Home</p>");
        res.end();
    }
};

createServer(requestListener).listen(PORT, () =>
    console.log(`Your request is Listening on localhost:${PORT}`)
);