How to Add Two Numbers in Console using Node.js ?

Adding two numbers using Node.js is a basic task that helps in understanding how to handle user input and process data within the Node.js environment. By following the steps in this guide, you'll learn how to create a simple Node.js application that reads numbers from the console, performs an addition operation, and displays the result.

Approach

To add two numbers in console using Node.js we will be using prompt package to get and process the input in console window. Then the string input is converted to float and added. The result is displayed using the console.log method.

Installation Steps

Step 1: Make a folder structure for the project.

mkdir myapp

Step 2: Navigate to the project directory

cd myapp

Step 3: Initialize the NodeJs project inside the myapp folder.

npm init -y

Step 4: Install the necessary packages/libraries in your project using the following commands.

npm install prompt

Project Structure:

The updated dependencies in package.json file will look like:

"dependencies": {
    "prompt": "^1.3.0"
  }

Example: Implementation to show how to add numbers in nodejs.

// app.js

// Require would make the prompt
// package available to use
const prompt = require("prompt");

// An utility function to add
// two numbers
function add() {
    // Start the prompt
    prompt.start();

    // Get two numbers/properties
    // from user num1 and num2
    prompt.get(
        ["num1", "num2"],
        function (err, res) {
            // To handle any error if occurred
            if (err) {
                console.log(err);
            } else {
                // By default get methods takes
                // input in string So parseFloat
                // is used to convert String
                // into Float
                var sum =
                    parseFloat(res.num1) +
                    parseFloat(res.num2);

                // Print the sum
                console.log( "Sum of " +
                        res.num1 + " and " +
                        res.num2 + " is " + sum
                );
            }
        }
    );
}

// Calling add function
add();

Step to run the application: Run the app.js file using the following command.

node app.js

Output: Now enter the user input and view output in the console.

So this is how you can add two numbers in the console using nodeJs. Prompts help us to take input from users. It also supports validation and defaults over the input.