Farm cookies on http://orteil.dashnet.org/cookieclicker/ !

farm-cookies.js

(() => {
  const cookie = document.getElementById('bigCookie');
  (function loop() {
      setTimeout(loop);
      cookie.dispatchEvent(new MouseEvent('click', { bubbles: true}));
  })();
})();


function itemRatio(item) {
  return item.cps(item) / item.price;
}

function getItemCps(item) {
  return item.cps(item);
}

(function loop() {
  const cookies = Game.cookies;
  const cps = Game.cookiesPs;

  const allItems = Object.keys(Game.ObjectsById).map((key) => {
    return Game.ObjectsById[key];
  });

  const itemsCanBuy = allItems.filter((item) => item.price < cookies);

  const bestItemCanBuy = bestItem(itemsCanBuy);
  const bestItemToBuy = bestItem(allItems);

  if (bestItemCanBuy && bestItemToBuy) {
    printItem('Best item to buy', bestItemToBuy);
    printItem('Best item can buy', bestItemCanBuy);

    const cpsWithBestItemCanBuyBought = cps + getItemCps(bestItemCanBuy);
    const cookiesWithBestItemCanBuyBought = cookies - bestItemCanBuy.price;

    console.log("ratio with bought best can buy: " + (bestItemToBuy.price - cookiesWithBestItemCanBuyBought) / cpsWithBestItemCanBuyBought );
    console.log("ratio with waiting: " + (bestItemToBuy.price - cookies) / cps)

    if (almostLessThan(
      (bestItemToBuy.price - cookiesWithBestItemCanBuyBought) / cpsWithBestItemCanBuyBought, 
      (bestItemToBuy.price - cookies) / cps
    )) {
      bestItemCanBuy.buy();
      window.bestItemCanBuyBought = (window.bestItemCanBuyBought || 0) + 1;
    } else if (bestItemToBuy.price <= cookies) {
      bestItemToBuy.buy();
    }
  }

  setTimeout(loop, 1000);

})();

function almostLessThan(a, b) {
  return a < 1.05 * b;
}

function printItem(label, item) {
  console.log(label + ' : ' + item.displayName + ' (ratio: ' + itemRatio(item));
}

function bestItem(items) {
  return items.reduce((max, current) => {
    if (itemRatio(max) < itemRatio(current)) {
      return current;
    }
    return max;
  }, items[0]);
}