Solution to rolls of coins workshop - JavaScript Alpharetta June 2019

js-alpharetta-rolls-of-coins.js

const coinsJar = [5, 10, 10, 25, 25, 25, 10, 5, 1, 1, 1, 25, 25];
// [...coinsJar].forEach
const coinRolls = { "1": 2, "5": 2, "10": 2, "25": 2 };

const coinsLabels = {
  "1": "Pennies",
  "5": "Nickels",
  "10": "Dimes",
  "25": "Quarters"
};

const coinsCount = coinsJar.reduce(groupBy, {});

//console.log(coinsCount);

const coinsInfo = Object.keys(coinsCount).map(key => {
  const totalCoins = coinsCount[key];
  const rollCount = coinRolls[key];
  const label = coinsLabels[key];

  const { quotient, remainder } = getQuotientRemainder(totalCoins, rollCount);
  const coinInfo = { label, quotient, remainder };

  return coinInfo;
});

//console.log(coinsInfo);

console.log(coinsInfo.map(displayRollMessage).join("\n"));

function groupBy(bag, coins) {
  !!bag[coins] ? (bag[coins] += 1) : (bag[coins] = 1);
  return { ...bag };
}

function getQuotientRemainder(x, y) {
  if (!y) {
    /// throw error
  }
  return { quotient: parseInt(x / y), remainder: x % y };
}

function displayRollMessage(info) {
  const { label, quotient: rolls, remainder: left } = info;
  return `${label}: ${rolls} rolls - ${left} left`;
}