aureooms/js-skip-list

import Node from './Node.js';

const node = (
    key = undefined,
    down = null,
    left = null,
    right = null,
    up = null,
) => {
    const newNode = new Node(key, down, left, right, up);
    if (down !== null) down.up = newNode;
    if (left !== null) left.right = newNode;
    if (right !== null) right.left = newNode;
    if (up !== null) up.down = newNode;
    return newNode;
};

export default node;