React JSX Calculate total

First, the language that I use is React JSX.

I have an error that says :

Cart_Index.jsx:27 Uncaught TypeError: cartItems.reduce is not a function.

    const calculateTotal = () => {
return cartItems.reduce((acc, item) => acc + item.price * item.quantity, 0);

};

I want to calculate the total with prices such as price * quantity.