cloneGraph.js

var cloneGraph = function (node) {
    if (!node) return;
    const visited = new Map();
    const dfs = (n) => {
        const nCopy = new Node(n.val);
        visited.set(n, nCopy);
        (n.neighbors || []).forEach(ne => {
            if (!visited.has(ne)) {
                dfs(ne);
            }
            nCopy.neighbors.push(visited.get(ne));
        })
    };
    dfs(node);
    return visited.get(node);
};