averageSpread.js

const getAvgSpread = prices => {
    let totalQty = 0, totalPrices = 0;
    for (let price in prices) {
        const qty = prices[price];
        totalQty += qty;
        totalPrices += parseFloat(price) * qty;
    }
    const avgPrice = parseFloat((totalPrices / totalQty).toFixed(8));
    return { avgPrice, totalQty };
};