stock-vsa-analyzer/src/indicators/mfi.js

export function calculateMFI(prices, volumes, period = 14) {
    const mfiValues = [];
    const typicalPrices = prices.map((price, index) => {
        return (price.high + price.low + price.close) / 3;
    });

    for (let i = 0; i < typicalPrices.length; i++) {
        if (i < period) {
            mfiValues.push(null);
            continue;
        }

        const gain = typicalPrices.slice(i - period + 1, i + 1).reduce((acc, price, index) => {
            return acc + (price > typicalPrices[i - period + index] ? volumes[i - period + index] : 0);
        }, 0);

        const loss = typicalPrices.slice(i - period + 1, i + 1).reduce((acc, price, index) => {
            return acc + (price < typicalPrices[i - period + index] ? volumes[i - period + index] : 0);
        }, 0);

        const moneyFlowRatio = gain / loss || 0;
        const mfi = 100 - (100 / (1 + moneyFlowRatio));
        mfiValues.push(mfi);
    }

    return mfiValues;
}