Node.js Creating Modules

Built-in modules contain most of the necessary functions. Sometimes, when implementing a Node.js application for a specific case, it may be necessary to retain the business logic separately. In this case, you will create a Node.js module that includes all the necessary functions.

In this Node.js tutorial, we will learn how to create Node.js modules and include them in Node.js files with examples.

Create a Node.js module

Node.js modules are .js files that have one or more functions.

The syntax for defining functions in Node.js modules is as follows:

exports –This is a keyword that tells Node.js that the feature is available outside the module.

Calculator - Node.js Module Example

Below is an example where we create a Calculator Node.js module with addition, subtraction, and multiplication functions and use the Calculator module in another Node.js file.

//　Returns the sum of two numbers
exports.add　=　function　(a,　b)　{　
　　　　return　a+b;　
　});　　
　
//　Returns the difference between two numbers
exports.subtract　=　function　(a,　b)　{　
　　　　return　a-b;　
　});　　
　
//　Returns the product of two numbers
exports.multiply　=　function　(a,　b)　{　
　　　　return　a*b;　
　});

var　calculator　=　require('./calculator';　
　
var　a=10,　b=5;　
　
console.log("Addition　:　"+calculator.add(a,b));　
console.log("Subtraction　:　"+calculator.subtract(a,b));　
console.log("Multiplication　:　"+calculator.multiply(a,b));

$　node　moduleExample.js　
Addition　:　15
Subtraction　:　5
Multiplication　:　50

Conclusion:

In this Node.js tutorial, we learned how to create Node.js modules and include the modules in another Node.js file through examples.