Two Sum Less Than K

let twoSumLessThanK = function(A, K) {
    let max = -1, start = 0, end = A.length - 1;
    A.sort((a, b) => b - a); //?

    while (start < end) {
        let sum = A[start] + A[end];
        if (sum < K) {
            max = Math.max(sum, max);
            end--;
        }
        else {
            start++;
        }
    }
    
    return max;
};