Get Input from Command Line in Node.js

What is Command Line Input?

Sometimes, we want to pass values directly while running a file from the terminal — like a username or a dynamic port number.


Create File: command-line-input.js

nodemon command-line-input.js anil sidhu

This runs the file and passes "anil" and "sidhu" as input arguments.


How to Get Command Line Input

const arg = process.argv;

console.log("-------", arg);


Output:------- [
'C:\\Program Files\\nodejs\\node.exe',
'C:\\Users\\sheet\\OneDrive\\Desktop\\turorial\\node 2025\\command-line-input.js',
'anil',
'sidhu'
]

🧾 process.argv is an array:

  1. Index 0 → Node path
  2. Index 1 → File path
  3. Index 2 onwards → Actual input values


Access Individual Input

console.log("-------", arg[3]);


Output:

------- sidhu
Note: Space-separated values are stored as separate elements in the array.


Example Use Case: Dynamic Port

const http = require("http");
const arg = process.argv;
const port = arg[2];

http
.createServer((req, resp) => {
resp.write("test input from cmd");
resp.end();
})
.listen(port);


Run this from Terminal:

nodemon command-line-input.js 4100

This will start a server on port 4100.