Best time to buy and sell stocks

bestTimeToBuy.js

/**
 * @param {number[]} prices
 * @return {number}
 */
var maxProfit = function(prices) {
    let max = 0;
    let buy = prices[0];

    for(let i=0; i<prices.length; i++) {
        if(prices[i] > buy) max = Math.max(max, prices[i] - buy);
        else buy = prices[i];
    }

    return max;
};

// loop through the array and check if the current price is more than the buy price
// then check if current price - buy price is greater than max, if yes then update max
// if current price is lesser than the buy price, then make the current price the buy price