Dijkstra's Algorithm in JavaScript.

dijkstra.js

var graph = [
  'AB6',
  'AC3',
  'BD6',
  'CD5',
  'CE9',
  'DF8',
  'DE3',
  'EG8',
  'FG2'
];

var parseEdge = (edge) => {
  var [left, right, ...cost] = edge;
  cost = parseInt(cost.join(''), 10);
  return { left, right, cost };
};

var addToMap = (map, origin, vertex, cost) => {
  (map[origin] = map[origin] || [])
    .push({ vertex, cost });
};

var graphToMap = (graph) => {
  var map = {};

  for (var edge of graph) {
    var { left, right, cost } = parseEdge(edge);

    addToMap(map, left, right, cost);
    addToMap(map, right, left, cost);
  }

  return map;
};

var tableToString = (table) => {
  return Object.keys(table)
    .map(vertex => {
      var { vertex: from, cost } = table[vertex];
      return `${vertex}: ${cost} via ${from}`;
    })
    .join('\n');
};

var tracePath = (table, start, end) => {
  var path = [];
  var next = end;
  while (true) {
    path.unshift(next);
    if (next === start) { break; }
    next = table[next].vertex;
  }

  return path;
};

var run = (graph, start, end) => {
  var map = graphToMap(graph);

  // console.log(map);

  var visited = [];
  var frontier = [start];
  var table = { [start]: { vertex: start, cost: 0 } };

  var vertex;
  while (vertex = frontier.shift()) {
    // Explore unvisited neighbors
    var neighbors = map[vertex]
      .filter(n => !visited.includes(n.vertex));

    // Add neighbors to the frontier
    frontier.push(...neighbors.map(n => n.vertex));

    var costToVertex = table[vertex].cost;

    for (let { vertex: to, cost } of neighbors) {
      var currCostToNeighbor = table[to] && table[to].cost;
      var newCostToNeighbor = costToVertex + cost;
      if (currCostToNeighbor == undefined ||
          newCostToNeighbor < currCostToNeighbor) {
        // Update the table
        table[to] = { vertex, cost: newCostToNeighbor };
      }
    }

    visited.push(vertex);
  }

  // console.log(table);

  console.log('Here you go:');
  console.log(tableToString(table));

  var path = tracePath(table, start, end);

  console.log('');
  console.log('Shortest path is:');
  console.log(path.join('->'));
};

run(graph, 'A', 'G');