4-hell.js

'use strict';

// Task: refactor callback hell code with named callbacks
// Restriction: you can change code only in "Usage" section

const getPurchase = (callback) => callback({
  Electronics: [
    { name: 'Laptop', price: 1500 },
    { name: 'Keyboard', price: 100 },
    { name: 'HDMI cable', price: 10 },
  ],
  Textile: [
    { name: 'Bag', price: 50 },
  ],
});

const iterateGroups = (order, callback) => {
  for (const groupName in order) {
    const group = order[groupName];
    callback(group);
  }
};

const groupTotal = (items, callback) => {
  let total = 0;
  for (const item of items) {
    total += item.price;
  }
  callback(total);
};

const budget = (limit) => {
  let balance = limit;

  const withdraw = (value, callback) => {
    const success = balance >= value;
    if (success) balance -= value;
    callback(success);
  };

  const rest = (callback) => callback(balance);

  return { withdraw, rest };
};

// Usage

const wallet = budget(1650);

getPurchase((purchase) => {
  let amount = 0;
  iterateGroups(purchase, (group) => {
    groupTotal(group, (subtotal) => {
      wallet.withdraw(subtotal, (success) => {
        if (success) amount += subtotal;
        wallet.rest((balance) => {
          console.log({ success, amount, subtotal, balance });
        });
      });
    });
  });
});