ExpressJS calculator via URL path

express-url-calculator.ts

/**
 * This script serves a simple calculator app which get the input from the URL path. 
 *
 * URL Format: http://locahost/:{port}/{number1}{math operator(+, -, * or /)}/{number2}
 * Example: http://localhost:3333/23+40
 */

const express = require('express')
const app = express()
const port = 3333

app.all('*', (req, res) => {

  const path = req.originalUrl.slice(-1) === '/'
    ? req.originalUrl.slice(1).substring(1) : req.originalUrl.slice(1)

  const operations = {
    '+': (a, b) => a + b,
    '-': (a, b) => a - b,
    '*': (a, b) => a * b,
    '/': (a, b) => a / b,
  }

  for (const operator in operations) {

    if (path.indexOf(operator) === -1) continue

    const numbers = path.split(operator).map(n => Number(n))

    const result = numbers.reduce((acc, curr) => {
        return operations[operator](acc, curr)
      }
    )
    
    res.json({ result: result, numbers: numbers, operator: operator })
    
    break
  }

  res.json({ result: "Error" })
})

app.listen(port, () => {
  console.log(`listening on port http://localhost:${port}/`)
})