I have an array of object as such

 "stock": [
    {
        "Quantity": -36,
        "Price": 74.55,
        "Consideration": 2683.8,
        "Direction": "SELL"
    },
    {
        "Quantity": -50,
        "Price": 74.14,
        "Consideration": 3707,
        "Direction": "SELL"
    },
    {
        "Quantity": 12,
        "Price": 77.15,
        "Consideration": -925.8,
        "Direction": "BUY"
    },
    {
        "Quantity": 15,
        "Price": 76.4,
        "Consideration": -1146,
        "Direction": "BUY"
    },
    {
        "Quantity": 19,
        "Price": 75.8,
        "Consideration": -1440.2,
        "Direction": "BUY"
    },
    {
        "Quantity": 20,
        "Price": 82.44,
        "Consideration": -1648.8,
        "Direction": "BUY"
    },
    {
        "Quantity": 10,
        "Price": 82.08,
        "Consideration": -820.8,
        "Direction": "BUY"
    },
    {
        "Quantity": 10,
        "Price": 82.49,
        "Consideration": -824.9,
        "Direction": "BUY"
    }
]

I am trying to subtract the PRICE property of each object from that of the preceding object and append the result as profit to that preceding object...

So basically from the first object in the array i'll have;

74.55 - 74.14 and the result will be appended to the second object as
profit: "result:

the only thing i've been only to think of is this

            let stockData = stock.map((stock) => {
            return {
                Quantity: stock.Quantity,
                Price: stock.Price,
                Consideration: stock.Consideration,
                Direction: stock.Direction,
            };
        });

        for (let i = 0; i < stockData.length; i++) {
            let profit = stockData[i].Price - stockData[i - 1].Price;
        }

        res.status(200).json({
            stock: stockData,
        });

And on the stockData[i - 1].Price i'm getting "can not read property Price of undefined"