javascript-rest-calculator

To create a RESTful calculator API in JavaScript, we'll use Node.js and Express. This API will take two numbers (num1 and num2) and an operation (add, subtract, divide, multiply) as query parameters, and return the result of the calculation.

Install nodejs

Optional: Install asdf tool-version manager

Run chmod +x deps.sh; ./deps.sh This will manage your nodejs versions

Guide to setup a calculator RESTful API:

1. Initialize a Node.js project:

   Open your terminal and run the following commands:

   mkdir javascript-rest-calculator
   cd javascript-rest-calculator
   npm init -y

2. Install Express:

        npm install express
        echo node_modules > .gitignore

3. Create the API:

   Create a file named index.js and add the following code:

        const express = require('express');
        const app = express();
        const port = 3000;
   
        app.get('/api/calculate', (req, res) => {
            const num1 = parseFloat(req.query.num1);
            const num2 = parseFloat(req.query.num2);
            const operation = req.query.operation;
   
            if (isNaN(num1) || isNaN(num2)) {
                return res.status(400).send('Both num1 and num2 should be valid numbers.');
            }
   
            let result;
            switch (operation) {
                case 'add':
                    result = num1 + num2;
                    break;
                case 'subtract':
                    result = num1 - num2;
                    break;
                case 'multiply':
                    result = num1 * num2;
                    break;
                case 'divide':
                    if (num2 === 0) {
                        return res.status(400).send('Cannot divide by zero.');
                    }
                    result = num1 / num2;
                    break;
                default:
                    return res.status(400).send('Invalid operation. Please use add, subtract, multiply, or divide.');
            }
   
            res.send(`${result}`);
        });
   
        app.listen(port, () => {
            console.log(`Calculator API is running on http://localhost:${port}`);
        });

4. Run the API:

   In your terminal, start the server by running:

   npm install
   node index.js

Your RESTful calculator API is now running on http://localhost:3000. You can test it using your browser or tools like Postman or curl.

For example, to add 5 and 3, you can visit:

http://localhost:3000/api/calculate?num1=5&num2=3&operation=add

http://localhost:3000/api/calculate?num1=5&num2=3&operation=subtract

http://localhost:3000/api/calculate?num1=5&num2=3&operation=multiply

http://localhost:3000/api/calculate?num1=5&num2=3&operation=divide

This will return:

8

Similarly, you can change the operation query parameter to subtract, multiply, or divide to perform different calculations.