dfs-with-david.js

function Node(val, num) {
  this.val = val;
  this.num = num;
}

var a = new Node('a', 1);
var b = new Node('b', 1);
var c = new Node('c', 1);
var d = new Node('d', 1);
var e = new Node('e', 1);
var f = new Node('f', 1);
var g = new Node('g', 1);
var g2 = new Node('g', 2);
var h = new Node('h', 1);

var graph = {
  a: [b, c, g],
  b: [d, e, f],
  c: [g2],
  g: [h]
};

function traverseDFS(root, target, graph, visited) {
  if (!visited) visited = {};
  if (root.val.toString() === target) {
    return root;
  }
  var graphRoot = graph[root.val];
  if (!graphRoot) return;

  for (var edge = 0; edge < graphRoot.length; edge++) {
    var graphRootEdge = graphRoot[edge];
    var result;
    if (!visited[graphRootEdge.val + graphRootEdge.num]) {
      visited[graphRootEdge.val + graphRootEdge.num] = true;
      result = traverseDFS(graphRootEdge, target, graph, visited);
    }
    if (result) return result;
  }
  return;
}

traverseDFS(a, 'g', graph);