dijkstra.js

let graph = {};
graph['start'] = {};
graph['start']['a'] = 6;
graph['start']['b'] = 2;
graph['a'] = {};
graph['a']['fin'] = 1;
graph['b'] = {};
graph['b']['a'] = 3;
graph['b']['fin'] = 5;
graph['fin'] = {};

let costs = {};
costs['a'] = 6;
costs['b'] = 2;
costs['fin'] = Infinity;

let parents = {};
parents['a'] = 'start';
parents['b'] = 'start';
parents['fin'] = null;

let processed = [];

function dijkstra() {
  let node = findLowerCostNode(costs);
  while(node !== null){
    let cost = costs[node];
    let neighbors = graph[node];
    for(let n in neighbors){
      let newCost = cost + neighbors[n];
      if(costs[n] > newCost){
        costs[n] = newCost;
        parents[n] = node;
      }
    }
    processed.push(node);
    node = findLowerCostNode(costs);
  }
}

function findLowerCostNode (costs) {
  let lowerCostNode = null;
  let lowerCost = Infinity;
  for(let node in costs){
    let cost = costs[node];
    if(cost < lowerCost && processed.indexOf(node) === -1){
      lowerCost = cost;
      lowerCostNode = node;
    }
  }
  return lowerCostNode;
}
dijkstra();