foo.diff

diff --git a/js/src/edge.js b/js/src/edge.js
index 7dc926b..67e776d 100644
--- a/js/src/edge.js
+++ b/js/src/edge.js
@@ -1,8 +1,8 @@
 var Edge = function(options) {
-    this.name = options.name;
+    this.props = options || {};
 
+    this.id = new Date().getTime();
     this.nodes = {};
-    this.deltav = options.deltav;
 };
 
 Edge.prototype = {
diff --git a/js/src/graph.js b/js/src/graph.js
index 00ab25c..09515b6 100644
--- a/js/src/graph.js
+++ b/js/src/graph.js
@@ -2,25 +2,44 @@ var Node = require('./node');
 var Edge = require('./edge');
 
 var Graph = function() {
-    this.nodes = [];
     this.edges = [];
 };
 
 // https://en.wikipedia.org/wiki/Graph_(abstract_data_type)
 Graph.prototype = {
-    addNode: function(node) {
-        this.nodes.push(node);
-    },
+    addEdge: function(edge, head_node, tail_node) {
+        edge.add(head_node, tail_node);
+
+        head_node.addEdge(edge);
+        tail_node.addEdge(edge);
 
-    addEdge: function(edge, node1, node2) {
-        edge.add(node1, node2);
         this.edges.push(edge);
     },
 
-    areAdjacent: function(node1, node2) {
+    areAdjacent: function(head_node, tail_node) {
         return this.edges.some(function(edge) {
-            return edge.areAdjacent(node1, node2);
+            return edge.areAdjacent(head_node, tail_node);
         });
+    },
+
+    // depth first search
+    walk: function(head_node, final_node) {
+        var current_node = head_node;
+        var total_value = 0;
+
+        current_node.visited = true;
+
+        current_node.edges.forEach(function(edge) {
+            var node = edge.nodes.tail;
+
+            if (!node.visited) {
+                total_value = edge.props.deltav;
+
+                total_value += this.walk(node, final_node)
+            }
+        }, this);
+
+        return total_value;
     }
 
     // delete(G, x, y): removes the edge from x to y, if it is there.
diff --git a/js/src/node.js b/js/src/node.js
index dbdddf4..9964b57 100644
--- a/js/src/node.js
+++ b/js/src/node.js
@@ -1,10 +1,14 @@
-var Node = function() {
+var Node = function(options) {
+    this.props = options || {};
+
     this.id = new Date().getTime();
+    this.edges = [];
+    this.visited = false;
 };
 
 Node.prototype = {
-    toString: function() {
-        return this.id;
+    addEdge: function(edge) {
+        this.edges.push(edge);
     }
 };
 
diff --git a/js/test/graph.js b/js/test/graph.js
index 9bac524..c838cde 100644
--- a/js/test/graph.js
+++ b/js/test/graph.js
@@ -1,4 +1,4 @@
-var test = require('tape');
+var describe = require('tape');
 var Graph = require('../src/graph');
 var Node = require('../src/node');
 var Edge = require('../src/edge');
@@ -14,36 +14,74 @@ var newEdge = function(options) {
     return new Edge(options);
 };
 
-test("creating a simple delta-v graph of the delta-v graph around kerbin", function(t) {
-    // http://i.imgur.com/duY2S.png
+describe("walking the graph", function(t) {
     var graph = new Graph();
 
-    var kerbin = newNode('Kerbin');
-    var low_kerbin_orbit = newNode('Low Kerbin Orbit');
-    var geostationary_transfer_orbit = newNode('GTO');
-    var mun_transfer = newNode('Mun Transfer');
+    describe("walking a simple linear graph", function(t) {
+        t.plan(5);
 
-    var kerbin_lko = newEdge({ deltav: 3800, name: 'kerbin-lko' });
-    var lko_gto = newEdge({ deltav: 670, name: 'lko-gto' });
-    var lko_mun_transfer = newEdge({ deltav: 190, name: 'lko-mun_transfer' });
+        // values taken from http://i.imgur.com/duY2S.png
+        var kerbin = newNode('Kerbin');
+        var low_kerbin_orbit = newNode('Low Kerbin Orbit');
+        var geostationary_transfer_orbit = newNode('GTO');
+        var mun_transfer = newNode('Mun Transfer');
 
-    t.plan(5);
+        var kerbin_lko = newEdge({ deltav: 3800, name: 'kerbin-lko' });
+        var lko_gto = newEdge({ deltav: 670, name: 'lko-gto' });
+        var lko_mun_transfer = newEdge({ deltav: 190, name: 'lko-mun_transfer' });
 
-    graph.addNode(kerbin);
-    graph.addNode(low_kerbin_orbit);
-    graph.addNode(geostationary_transfer_orbit);
-    graph.addNode(mun_transfer);
+        graph.addEdge(kerbin_lko, kerbin, low_kerbin_orbit);
+        graph.addEdge(lko_gto, low_kerbin_orbit, geostationary_transfer_orbit);
+        graph.addEdge(lko_mun_transfer, low_kerbin_orbit, mun_transfer);
 
-    graph.addEdge(kerbin_lko, kerbin, low_kerbin_orbit);
-    graph.addEdge(lko_gto, low_kerbin_orbit, geostationary_transfer_orbit);
-    graph.addEdge(lko_mun_transfer, low_kerbin_orbit, mun_transfer);
+        t.true(graph.areAdjacent(kerbin, low_kerbin_orbit));
+        t.true(graph.areAdjacent(low_kerbin_orbit, geostationary_transfer_orbit));
+        t.true(graph.areAdjacent(low_kerbin_orbit, mun_transfer));
 
-    t.true(graph.areAdjacent(kerbin, low_kerbin_orbit));
-    t.true(graph.areAdjacent(low_kerbin_orbit, geostationary_transfer_orbit));
-    t.true(graph.areAdjacent(low_kerbin_orbit, mun_transfer));
+        t.false(graph.areAdjacent(kerbin, geostationary_transfer_orbit));
+        t.false(graph.areAdjacent(kerbin, mun_transfer));
 
-    t.false(graph.areAdjacent(kerbin, geostationary_transfer_orbit));
-    t.false(graph.areAdjacent(kerbin, mun_transfer));
+        t.end();
+    });
+
+    describe("walking a graph with three branches", function(t) {
+        t.plan(1);
+
+        // values taken from http://i.imgur.com/SqdzxzF.png
+        var earth = newNode('Earth');
+        var leo = newNode('Low Earth Orbit');
+        var geo_transfer = newNode('Geostationary Transfer');
+        var geostationary = newNode('Geostationary Orbit');
+        var moon_transfer = newNode('Moon Transfer');
+        var low_moon_orbit = newNode('Low Moon Orbit');
+        var earth_escape = newNode('Earth Escape');
+        var mars_transfer = newNode('Mars Transfer');
+
+        var low_earth_orbit = newEdge({ deltav: 9400, name: 'low_earth_orbit' });
+
+        var leo_geo_transfer = newEdge({ deltav: 2440, name: 'leo-geo_transfer' });
+        var geo_transfer_geo_orbit = newEdge({ deltav: 1470, name: 'geostationary_transfer-geostationary_orbit' });
+
+        var leo_moon_transfer = newEdge({ deltav: 3260, name: 'leo-moon_transfer' });
+        var moon_transfer_lmo = newEdge({ deltav: 680, name: 'moon_transfer-low_moon_orbit' });
+
+        var leo_earth_escape = newEdge({ deltav: 3210, name: 'leo-earth_escape' });
+
+        var earth_escape_mars_transfer = newEdge({ deltav: 390, name: 'earth_escape-mars_transfer' });
+
+        graph.addEdge(low_earth_orbit, earth, leo);
+
+        graph.addEdge(leo_geo_transfer, leo, geo_transfer);
+        graph.addEdge(geo_transfer_geo_orbit, geo_transfer, geostationary);
+
+        graph.addEdge(leo_moon_transfer, leo, moon_transfer);
+        graph.addEdge(moon_transfer_lmo, moon_transfer, low_moon_orbit);
+
+        graph.addEdge(leo_earth_escape, leo, earth_escape);
+        graph.addEdge(earth_escape_mars_transfer, earth_escape, mars_transfer);
+
+        var tot = graph.walk(earth, mars_transfer);
+    });
 
     t.end();
 });
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