How to start a new NPM project

• Install node and npm. They are packaged together here.
• Open a terminal window and find the directory you want to work in.
• Run npm init in that folder and answer the questions. This will create a package.json file.
• Create an index.js file. This is where we will start writing code!

You dont need a package.json file to run a node script. You can just create a script and run node script.js. However you need a package.json to install dependencies like third party libraries.

Lets make a simple API server!

• Install the third-party library "ExpressJS" which lets us run a node server.
• Run npm install express. This will add Express to our package.json file and will include the library in the node_modules file.
• Inside our index.js file include the following code:

const express = require('express')
const app = express()
const port = 3000

app.get('/', (req, res) => {
  res.send('Hello World!')
})

app.listen(port, () => {
  console.log(`Example app listening at http://localhost:${port}`)
})

Source

• Modify the package.json's script block:

"scripts": {
  "start": "node index.js"
},

• Run npm start. Alternatively you can just run node index.js, but using the package.json is preferable.
• Visit http://localhost:3000/ and see it in action!