Best time to buy & sell stock

You are given an array prices where prices[i] is the price of a given stock on the ith day.

You want to maximize your profit by choosing a single day to buy one stock and choosing a different day in the future to sell that stock.

Return the maximum profit you can achieve from this transaction. If you cannot achieve any profit, return 0.

Example 1:

Input: prices = [7,1,5,3,6,4]

Output: 5

Explanation: Buy on day 2 (price = 1) and sell on day 5 (price = 6), profit = 6-1 = 5. Note that buying on day 2 and selling on day 1 is not allowed because you must buy before you sell.

/**
 * @param {number[]} prices
 * @return {number}
 */
var maxProfit = function(prices) {
    if (!prices || prices.length < 2) {
        return 0;
    }

    let minPrice = prices[0];
    let maxProfitAfterSell = 0;

    for (let i = 0; i < prices.length; i++) {
        minPrice = Math.min(minPrice, prices[i]);
        maxProfitAfterSell = Math.max(maxProfitAfterSell, prices[i] - minPrice);
    }

    return maxProfitAfterSell;
};