🗂 Overview to NodeJS/Express

Repo made to learn NodeJS. This will also include making restful APIs and dealing with requests and responses.

❗ℹ️ Important Info

Content-Type for Headers

• text/html
• application/json
• image/jpeg
• image/png
• image/gif
• audio/mpeg
• video/mp4
• application/javascript
• text/css
• text/plain

Setting Headers

• res.setHeader(name, value) - Sets a response header.
• res.getHeader(name) - Retrieves a specific response header.
• res.removeHeader(name) - Removes a response header.
• res.writeHead(statusCode, headers) - Sets status code and multiple headers at once.

Sending Data

• res.write(chunk) - Writes data to the response body.
• res.end([data]) - Signals the response is complete, optionally sending a final chunk of data.

Handling Status Codes

• res.statusCode = number - Sets the HTTP status code.
• res.statusMessage = "message" - Customizes the status message.

Response Control

• res.flushHeaders() - Forces headers to be written immediately.
• res.hasHeader(name) - Checks if a header exists.

HTTP Methods

• GET - Retrieves data from the server.
• POST - Sends data to the server to create a new resource.
• PUT - Updates or replaces an existing resource on the server.
• HEAD - Similar to GET, but only retrieves headers (no body).
• DELETE - Removes a resource from the server.
• PATCH - Partially updates an existing resource.
• OPTIONS - Returns the supported HTTP methods for a resource.

Reference to Article: The 7 Methods

🛠️ 🐛 Progress/Bugs

⚙️ Creating a basic server and it's setup:

╰┈➤

const http = require("http");

const server = http.createServer((req, res) => {
  res.setHeader("Content-Type", "text/plain");
  res.end("Hello World\n");
});

const PORT = 3000;

server.listen(PORT, () => {
  console.log(`Server running at http://localhost:${PORT}/`);
});

🚧 Running the server with Nodemon for effective development.

╰┈➤

"scripts": {
  "start": "node server.js",
  "dev": "nodemon server.js"
}

# This will run nodemon server.js for updates on save
npm run dev

🧐 Test your running server/setup with Postman.

╰┈➤

🗂️ Let's make our own API.

╰┈➤

const http = require("http"); // importing the http module from node:http

const arrayList = [
  { id: 1, item: "item 1" },
  { id: 2, item: "item 2" },
  { id: 3, item: "item 3" },
  { id: 4, item: "item 4" },
]; // array list

const server = http.createServer((req, res) => {
  // using the createServer method from http module
  res.setHeader("Content-Type", "application/json"); // setting the response for the header

  res.end(
    // ending/final response
    JSON.stringify(
      // This is to convert object to string, err: The "chunk" argument must be of type string or an instance of Buffer or Uint8Array.
      {
        sucess: true,
        method: req.method,
        data: arrayList,
      }
    )
  );
});

const PORT = 3000; // setting port number

server.listen(PORT, () => {
  // listen to the port and then console log message
  console.log(`Server running at http://localhost:${PORT}/`);
});

⛁ Working w/ Routes in ExpressJS

╰┈➤

⚙️ Setup + Environment Variables

• Download and install the following npm packages:

# This will install express and we need to make a .env file
npm install express dotenv

• Now we alter our code to use NodeJS w/ Express.

server.js

const http = require("http"); // importing the http module from node:http
require("dotenv").config(); // import environment variables from .env file
const app = require("./app"); // import data from index.js

const server = http.createServer(app); // throw data from express app to http server

server.listen(process.env.PORT, () => {
  // listen to the port and then console log message
  console.log(`Server running at http://localhost:${process.env.PORT}/`);
});

app/index.js

const express = require("express");
// import { express } from 'express';

const app = express();

app.get("/", (req, res) => {
  // use '/' route
  res.status(200).json({
    // get status 200 - success and return data into JSON
    message: "GET - root",
    metadata: {
      hostname: req.hostname,
      method: req.method,
    },
  });
});

module.exports = app; // export app, used in server.js file

⚠️ Working w/ Jest

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• npm i -D jest

math.test.js

• Writing tests for math objects.

const { add, subtract, multiply, divide, sqrt, max } = require("./math");

describe("Testing basic math objects", () => {
  test("Should add two numbers", () => {
    const result = add(1, 2);
    expect(result).toBe(3);
  });

  test("Should subtract two numbers", () => {
    const result = subtract(2, 1);
    expect(result).toBe(1);
  });

  test("Should multiply two numbers", () => {
    const result = multiply(2, 3);
    expect(result).toBe(6);
  });

  test("Should divide two numbers", () => {
    const result = divide(6, 3);
    expect(result).toBe(2);
  });
});

describe("Testing advanced math objects", () => {
  test("Should find the sqrt of a number", () => {
    const result = sqrt(4);
    expect(result).toBe(2);
  });

  test("Should find the max of two numbers", () => {
    const result = max(1, 2);
    expect(result).toBe(2);
  });
});

math.js

// >>> Basic Math Objects
const add = (a, b) => {
  return a + b;
};

const subtract = (a, b) => {
  return a - b;
};

const multiply = (a, b) => {
  return a * b;
};

const divide = (a, b) => {
  return a / b;
};

add(1, 2); // result should be 3
subtract(2, 1); // result should be 1
multiply(2, 3); // result should be 6
divide(6, 3); // result should be 2

// >>> Advanced Math Objects
const sqrt = (a) => {
  return Math.sqrt(a);
};

const max = (a, b) => {
  return Math.max(a, b);
};

sqrt(4); // result should be 2
max(1, 2); // result should be 2

module.exports = {
  add,
  subtract,
  multiply,
  divide,
  sqrt,
  max,
};