How to Create Modules in Node.js ?
Modules are the collection of JavaScript codes in a separate logical file that can be used in external applications on the basis of their related functionality. Modules are popular as they are easy to use and reusable. To create a module in Node.js, you will need the exports keyword. This keyword tells Node.js that the function can be used outside the module.
Syntax:
exports.function_name = function(arg1, arg2, ....argN) { // function body };
Example of a custom node module:
Create a file that you want to export
javascript
// File name: calc.js exports.add = function (x, y) { return x + y; }; exports.sub = function (x, y) { return x - y; }; exports.mult = function (x, y) { return x * y; }; exports.div = function (x, y) { return x / y; }; |
Use the ‘require’ keyword to import the file
javascript
// File name: App.js const calculator = require( './calc' ); let x = 50, y = 20; console.log( "Addition of 50 and 20 is " + calculator.add(x, y)); console.log( "Subtraction of 50 and 20 is " + calculator.sub(x, y)); console.log( "Multiplication of 50 and 20 is " + calculator.mult(x, y)); console.log( "Division of 50 and 20 is " + calculator.div(x, y)); |
Output:
Addition of 50 and 20 is 70 Subtraction of 50 and 20 is 30 Multiplication of 50 and 20 is 1000 Division of 50 and 20 is 2.5