bfs.js

class Graph {

  constructor(){
    this.nodes = {};
  }
  addNode(n){
    if (!this.nodes[n]) this.nodes[n] = [];
  }
  addEdge(a,b){
    this.nodes[a].push(b);
  }

}

let g = new Graph();

g.addNode(0);
g.addNode(1);
g.addNode(2);
g.addNode(3);


g.addEdge(0, 1) 
g.addEdge(0, 2) 
g.addEdge(1, 2) 
g.addEdge(2, 0) 
g.addEdge(2, 3) 
g.addEdge(3, 3) 


function bfs(graph,node){
  const visited = new Set();
  let q = [node];
  visited.add(node);

  while (q.length) {
    let newNode = q.pop();
    console.log(newNode);
    for (let adjNode of graph.nodes[newNode]){
      if (!visited.has(adjNode)){
        q.unshift(adjNode);
        visited.add(adjNode);
      }
    }
  }
}


bfs(g,2);