Session-1.md

Node js -

Session 1

• Date: 09.11.2020

Overview / Topics discussed

• What is node js and npm
• Express framework over node js
• Build a basic server
• More about node js being event-driven and async
• Create a connection to mongo db using npm library mongoose
• How to create a route to customize response to incoming requests

---

What is node js and npm

• Node.js is a free, open-sourced, cross-platform JavaScript run-time environment that lets developers write command line tools and server-side scripts outside of a browser.
• npm is the package manager for the Node JavaScript platform. It puts modules in place so that node can find them.

Express framework

• A web framework for Node.js
• Thanks to express being fast, unopinionated and minimalist, node js becomes much easier to use.

Build a basic server and about node js being event-driven

• In your command line

npm init

in your project directory to initialise the directory you are in as a node js folder.

• This creates a package.json file which looks something like this:

{
  "name": "note-app",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "repository": {
    "type": "git",
    "url": "git+https://github.com/Pragati1610/note-app.git"
  },
  "author": "Pragati",
  "license": "ISC"
}

Going back to your command line, do

npm install express

to include express as a dependency in our project folder.
You will see it get added to package.json in the dependencies as a key-value pair with it's version mentioned.
Now create a file to act like a server in our backend I'm naming it server.js

The following contents go in it.

const express = require('express'); // to use a library we need to require it

const app = express(); // creates an instance of app by calling express method
const port = process.env.PORT || 3000; // you can set the port to the default env or 3000

app.listen(port, () => { // creates a server to listen to port and triggers a call back function when the action is performed
    console.log(`server started at ${port}`); // body of the call back function 
});

Next run your server using

node server

You should see server started at 3000 printed in your terminal
✨ your first node js server

• Create a connection to mongo db using npm library mongoose
  • Get the connection link to mongo atlas
  • Create a .env to hold your env vars
  • Add the link there
  • install mongoose by:

  npm i mongoose
  

  • add a snippet (to connect to your db) to server.js which would finally look something like this:

  const express = require('express');
  const mongoose = require('mongoose');
  
  mongoose.connect(process.env.DB_URL, {
      useCreateIndex: true,
      useNewUrlParser: true,
      useUnifiedTopology: true,
  }).then(() => {
      console.log('connection to db established');
  }).catch(err => {
      console.log(err)
  });
  
  const app = express();
  const port = process.env.PORT || 3000;
  
  
  app.listen(port, () => {
      console.log(`server started at ${port}`);
  });

We are almost there, one last section and you would be able to to customize your response to incoming requests

How to create a route

• Require body-parser to be able to take json data from the user

npm install body-parser

const express = require('express');
const mongoose = require('mongoose');
const dotenv = require('dotenv');
const bodyparser = require("body-parser");

const authRoute = require('./routes/authRoute');

dotenv.config();

mongoose.connect(process.env.DB_URL, {
    useCreateIndex: true,
    useNewUrlParser: true,
    useUnifiedTopology: true,
}).then(() => {
    console.log('connection to db established');
}).catch(err => {
    console.log(err)
});

const app = express();
const port = process.env.PORT || 3000;

app.use(bodyparser.json());

app.post('/user', (req, res)=>{  // specify the route you want to hit to when a request is sent to localhost:3000/user
  const {name} = req.body;       // destructure name from req.body and 
  res.send(`Name is ${name}`);   // send it back to the user ~ this part is the customizable, you can do whatever you want to respond the user when a request is sent to this route
});

app.listen(port, () => {
    console.log(`server started at ${port}`);
});

Session-2 :

• login sign-up routes
• jwt
• get and post routes
• testing using postman
• patch and delete routes
• learning how to view your db using mongo dB compass