Graphs

class Graph { 
  constructor() { 
    this.numberOfNodes = 0; 
    this.adjacentList = {}; 
  } 
  addVertex(node)  { 
    this.adjacentList[node] = []; 
    this.numberOfNodes++;
  } 
  addEdge(node1, node2) { 
    //uniderected Graph 
    this.adjacentList[node1].push(node2); 
    this.adjacentList[node2].push(node1); 
  } 
  showConnections() { 
    const allNodes = Object.keys(this.adjacentList); 
    for (let node of allNodes) { 
      let nodeConnections = this.adjacentList[node]; 
      let connections = ""; 
      let vertex;
      for (vertex of nodeConnections) {
        connections += vertex + " ";
      } 
      console.log(node + "-->" + connections); 
    } 
} 
} 

var myGraph = new Graph();
myGraph.addVertex('0');
myGraph.addVertex('1');
myGraph.addVertex('2');
myGraph.addVertex('3');
myGraph.addVertex('4');
myGraph.addVertex('5');
myGraph.addVertex('6');
myGraph.addEdge('3', '1'); 
myGraph.addEdge('3', '4'); 
myGraph.addEdge('4', '2'); 
myGraph.addEdge('4', '5'); 
myGraph.addEdge('1', '2'); 
myGraph.addEdge('1', '0'); 
myGraph.addEdge('0', '2'); 
myGraph.addEdge('6', '5');

myGraph.showConnections();