heap-data-structure/d-ary-heap

/**
 * Computes which child is the smallest according
 * to a comparison function.
 *
 * Hypothesis : i < j i.e. there should be at least one child
 *
 * @param {int} arity arity of the heap
 * @param {function} compare the comparison function
 * @param {function} swap the swap function
 * @param {array} a the array where the heap is stored
 * @param {int} i is the first child
 * @param {int} j - 1 is the last leaf
 */

export default function nextchild(arity, compare, swap, a, i, j) {
    const k = i + Math.min(arity, j - i);

    let best = i;

    for (++i; i < k; ++i) {
        if (compare(a[i], a[best]) < 0) {
            best = i;
        }
    }

    return best;
}