Modules in Node.js

Built-in Modules

Node.js comes with several built-in modules like fs, http, path, and os.

Example using the fs module to read a file:

const fs = require("fs");
fs.readFile("example.txt", "utf8", (err, data) => {
  if (err) {
    console.error(err);
    return;
  }
  console.log(data);
});

Creating Custom Modules

Create math.js:

exports.add = (a, b) => a + b;
exports.subtract = (a, b) => a - b;

Use it in app.js:

const math = require("./math");
console.log(math.add(5, 3));