5-errors.js

'use strict';

// Task: rewrite error handling to use callback-last-error-first
// contract to return errors instead of throwing them.
// So remove all try/catch blocks and pass errors to callbacks.
// Hint: You may also use error.cause to wrap escalated errors.
// Extra credit task: use AggregateError to combine escalated errors.
// Extra credit task: fix eslint error: "Function declared in a loop
//   contains unsafe references to variable(s) 'total'  no-loop-func"

const MAX_PURCHASE = 2000;

const calculateSubtotal = (goods, callback) => {
  let amount = 0;
  for (const item of goods) {
    if (typeof item.name !== 'string') {
      throw new Error('Noname in item in the bill');
    }
    if (typeof item.price !== 'number') {
      throw new Error(`${item.name} price expected to be number`);
    }
    if (item.price < 0) {
      throw new Error(`Negative price for ${item.name}`);
    }
    amount += item.price;
  }
  callback(amount);
};

const calculateTotal = (order, callback) => {
  const expenses = new Map();
  let total = 0;
  const calc = (groupName) => (amount) => {
    total += amount;
    expenses.set(groupName, amount);
  };
  for (const groupName in order) {
    const goods = order[groupName];
    calculateSubtotal(goods, calc(groupName));
    if (total > MAX_PURCHASE) {
      throw new Error('Total is above the limit');
    }
  }
  return callback({ total, expenses });
};

const purchase = {
  Electronics: [
    { name: 'Laptop', price: 1500 },
    { name: 'Keyboard', price: 100 },
    { name: 'HDMI cable' },
  ],
  Textile: [
    { name: 'Bag', price: 50 },
    { price: 20 },
  ],
};

try {
  console.log(purchase);
  calculateTotal(purchase, (bill) => {
    console.log(bill);
  });
} catch (error) {
  console.log('Error detected');
  console.error(error);
}