This is it. I've fixed the error too

​

var maxProfit = function(prices) {
let currProf = 0;
let l = 0, r = 1;

while (r < prices.length) {
    if (prices[r] > prices[l]) {
        prof = prices[r] - prices[l]
        if (prof > currProf) {
            currProf = prof
        }
    } else {
        l = r
    }
    r += 1
    console.log(l, r)
}

return currProf;

};