weighted.js

class WeightedGraph {
  constructor(){
    this.adjacencyList = {};
  }
  addVertex(name){
    this.adjacencyList[name] = [];
  }
  addEdge(vertex1, vertex2, weight){
    this.adjacencyList[vertex1].push({node:vertex2, weight});
    this.adjacencyList[vertex2].push({node:vertex1, weight});
  }
  Dijkstra(start, finish){
    const distances = {};
    const nodes = new PriorityQueue();
    const previous = {};
    let path = []; // to return at the end
    let smallest;

    // Build up initial state
    for(let vertex in this.adjacencyList){
      if(vertex === start){
        distances[vertex] = 0;
        nodes.enqueue(vertex, 0);
      } else {
        distances[vertex] = Infinity;
        nodes.enqueue(vertex, Infinity);
      }
      previous[vertex] = null;
    }
    // run as long as there is something in the queue
    while(nodes.values.length){
      smallest = nodes.dequeue().val;
      if(smallest === finish){
        //We are done! Build up path to return at the end
        while(previous[smallest]){
          path.push(smallest);
          smallest = previous[smallest];
        }
        break;
      }
      if(smallest || distances[smallest] !== Infinity){
        for(let neighbor in this.adjacencyList[smallest]){
          //Find neighboring node
          let nextNode = this.adjacencyList[smallest][neighbor];
          console.log(nextNode);
          //calculate new distances to neighboring node
          let candidate = distances[smallest] + nextNode.weight;
          let nextNeighbor = nextNode.node;
          if(candidate < distances[nextNeighbor]){
            //updating new smallest distance to neighbor
            distances[nextNeighbor] = candidate;
            //updating previous - How we got to neighbor
            previous[nextNeighbor] = smallest;
            //enqueue in priority queue with new priority
            nodes.enqueue(nextNeighbor, candidate);
          }
        }
      }
    }
    console.log(distances)
    console.log(previous);
    return path.concat(smallest).reverse();
  }
}

class PriorityQueue{
  constructor(){
    this.values = [];
  }
  enqueue(val, priority){
    this.values.push({val, priority});
    this.sort();
  };
  dequeue(){
    return this.values.shift();
  };
  sort(){
    this.values.sort((a,b) => a.priority - b.priority);
  };
}

let graph = new WeightedGraph();

graph.addVertex("A");
graph.addVertex("B");
graph.addVertex("C");
graph.addVertex("D");
graph.addVertex("E");
graph.addVertex("F");

graph.addEdge("A", "B", 4);
graph.addEdge("A", "C", 2);
graph.addEdge("B", "E", 3);
graph.addEdge("C", "D", 2);
graph.addEdge("C", "F", 4);
graph.addEdge("D", "E", 3);
graph.addEdge("D", "F", 1);
graph.addEdge("E", "F", 1);

console.log(graph.Dijkstra("A", "E"));