Understanding Node Modules

Starting a Node application

1. create a folder - node-examples
2. now intiliaze the package.json by typing - npm init

3. Accept the standard defaults suggested and the update the package.json
   file until you end up with the file containing the following
   {
   "name": "node-examples",
   "version": "1.0.0",
   "description": "Simple Node Examples",
   "main": "index.js",
   "scripts": {
   "test": "echo \"Error: no test specified\" && exit 1",
   "start": "node index"
   },
   "author": "Sonu Jha",
   "license": "ISC"
   }

4. now create a file name index.js

var rect = {
perimeter : (x,y) =>(2*(x+y)),
area: (x,y) => (x*y)
};

function solveRect(l,b) {
console.log("Solving for rectangle with l = " + l + " and b = " + b);
if (l <= 0 || b <= 0) {
console.log("Rectangle dimensions should be greater than zero: l = "
+ l + ", and b = " + b);
}
else {
console.log("The area of the rectangle is " + rect.area(l,b));
console.log("The perimeter of the rectangle is " + rect.perimeter(l,b));
}
}
solveRect(2,4);
solveRect(3,5);
solveRect(0,5);
solveRect(-3,5);

1. To run the Node Application type the following at prompt npm start

A simple Node Module

1. Now create a file name rectangle.js and the following code to it:

exports.perimeter = (x, y) => (2*(x+y));

exports.area = (x, y) => (x*y);

1. Then Update index.js as follows :

var rect = require('./rectangle');

In Conclusion, A Node Modules are js files that are imported using require() function to use the functionalty.