How to Create Express Backend program

1. lets understand step by step:-

2. First we need to go to the directory and folder-where we want to create our node js program so we will use command prompt in our pc. ( let suppose FSJS is the folder and the location is desktop so can write )

   cd location / folder name 
   ( cd Desktop/FSJS )-code
   

3. Then we need to make a directory called as Socialmediaapp so next we need to wright on command prompt.

   folder name/directory name  
   ( FSJS mkdir Socialmediaapp )-code
   

   This is the directory name where i am going create myapp So to go into the directory i am going wright

   FSJS cd Socialmediaapp
   Socialmediaapp code .
   

4. Then we will wright

   Socialmediaapp npm init
   

   when we wright npm init ,it will going to ask certain Question and if you want to edit or update anything Like (program name author name you can do it as you like ) and if you want default setting or avoid this questionnaires you can simply wright

   Socialmediaapp npm init -y
   

5. Then we well the packeage.json file which contains all details of the program

{
  "name": "socialmediaapp",
  "version": "1.0.0",
  "description": "My First Backend program",
  "main": "index.js",
  "scripts": {
    "test": "echo\"Error: no test specified \"&& exit 1"},
  "author": "Rahul Parmar",
  "license": "ISC",

so now we can say that we created our first node js app After writing a simple code.

cd Desktop/FSJS 
FSJS mkdir Socialmediaapp 
FSJS cd Socialmediaapp 
Socialmediaapp code . 
Socialmediaapp npm init

Now We need to create Index.js file but ... why?

Ans: Because when we wright npm start ,so it is going to go inside script and search for command which is going to run the script and search the script file which is going to run . so as per previous program we don't have any start command and script file so we have to create a index.js file(it is also known as entry point) and we need do some changes in previous code and need to add a start command and index.js file in the program then the code will be as follows -To run this node js program first we need to install an famous app called as Express app so we need to wright

socialmediaapp npm i express
 socialmediaapp npm i nodemon 
socialmediaapp npm start

{
  "name": "socialapp",
  "version": "1.0.0",
  "description": "My First Backend program",
  "main": "index.js",
  "scripts": {
    "start": "nodemon index.js"
  },
  "author": "Rahul Parmar",
  "license": "ISC",
  "dependencies": {
    "express": "^4.18.2",
    "nodemon": "^2.0.22"
  }
}

index.js

console.log("hello world");

Output

hello would

To avoid repetition of run the program when we can make any changes ,we can install NODEMON.

• what nodemon do? Ans: nodemon is a tool that helps develop Node.js based applications by automatically restarting the node application when file changes in the directory are detected. and it can be install just to write "npm i nodemon"

  Thank you