Node.js: calcolare il valore dell'IVA

In Node.js possiamo calcolare il valore dell'IVA con ExpressJS.

Creiamo la nostra classe di utility:

'use strict';

class Vat {
  constructor(value) {
    this.value = ((value / 100) + 1);
  }
  add(amount) {
    return (amount * this.value);
  }
  remove(amount) {
    return (amount / this.value);
  }
  amount(total) {
    let diff = (total / this.value);
    return (total - diff);
  }
}

module.exports = Vat;

Quindi creiamo la nostra route:

'use strict';

const express = require('express');
const app = express();
const Vat = require('./classes/vat');
const actions = ['add','remove','amount'];

app.post('/calculate', (req, res) => {
    let action = req.body.action;
    let value = parseInt(req.body.value, 10);
    let amount = Number(req.body.amount);

    if(actions.indexOf(action) !== -1) {
        let vatInstance = new Vat(value);
        let output = vatInstance[action](amount);
        res.json({vat: output});
    } else {
      res.sendStatus(403);
    }

});