CoinChange.js

class CoinChange {
  constructor(changes) {
    this.coins = 0;
    this.changes = changes;
    this.output = {};
  };
  getEquivalence(equivalence) {
    let output = 0;
    if(this.coins / equivalence > 1){
      output = (this.coins - (this.coins % equivalence)) / equivalence;
      this.coins = this.coins % equivalence;
    }
    return output;
  };
  getChanges(coins) {
    const me = this;
    me.coins = coins;
    Object.keys(me.changes).forEach((k, v, er) => {
      me.output[k] = me.getEquivalence(me.changes[k]);
    });

    return me.output;
  };
}

class CoinChangeByCountry {
  constructor() {
    this.config = {};
  };
  addCountry(country, config) {
    this.config[country] = new CoinChange(config);
  };
  getChanges(country, coins) {
    return this.config[country].getChanges(coins);
  };
}

const countries = new CoinChangeByCountry();

countries.addCountry('US', {
  Dollar: 100,
  Quarter: 25,
  Dime: 10,
  Nickel: 5,
  Cents: 1
});