BFS(Breadth First Search)

const bfs = (startNode) => {
  const visited = [];
  const needVisit = [];
  needVisit.push(startNode);

  while (needVisit.length !== 0) {
    const node = needVisit.shift();
    if (!visited.includes(node)) {
      visited.push(node);
      needVisit.push(...graph[node]);
    }
  }
  return visited;
};