Solution to vending machine challenge - JavaScript Alpharetta June 2019

js-alpharetta-vm.js

const VM = function(inventory) {
  var drinks = inventory || null;

  if (!drinks) {
    throw new Error("No inventory: Cannot add a new VM");
  }

  const drinksKeys = Object.keys(drinks);

  var sale = function(pid) {
    if (!drinks[pid]) {
      return;
    }

    if (drinks[pid].stock > 0) {
      drinks[pid].stock--;
      return `1 ${drinks[pid].name} - Thank you, come again!!`;
    } else {
      drinks[pid].stock = 0;
      return ` ${drinks[pid].name} is out of stock :( Come back tomorrow`;
    }
  };

  var stock = function() {
    const total = drinksKeys.reduce((c, n) => c + drinks[n].stock, 0);
    return total;
  };

  return { sale };
};

const drinks = {
  1: { name: "Mango Juice", stock: 2 },
  2: { name: "Banana Smoothies", stock: 2 },
  3: { name: "Guava Mix", stock: 1 },
  4: { name: "Citrus Blend", stock: 3 }
};

const vm = VM(drinks);