Add method for serializing network

I still have to write one to undo it, but this is a step towards #18

index.html

@@ -169,6 +169,8 @@ <h1>Wikipedia Map</h1>
   <script type="text/javascript" src="./js/main_functions.js"> </script>
   <!-- Load the main script -->
   <script type="text/javascript" src="./js/main.js"> </script>
+  <!-- Load serialization functions -->
+  <script type="text/javascript" src="./js/network_serialize.js"> </script>
   <!-- Build help popup -->
   <script type="text/javascript" src="./js/help.js"> </script>
   <!-- Load bindings -->

js/network_serialize.js

@@ -0,0 +1,57 @@
+// Functions for the serialization of a vis.js network. This allows for storing
+// a network as JSON and then loading it back later.
+
+function howConcise() {
+  // Debugging functions to see the number of characters saved by only including
+  // select values in the JSON output.
+  var unAbbreviatedLength = JSON.stringify(nodes._data).length +
+                            JSON.stringify(edges._data).length +
+                            JSON.stringify(startpages).length;
+  var abbreviatedLength = networkToJson().length;
+  var bytesSaved = unAbbreviatedLength - abbreviatedLength;
+  return "Abbreviation takes it from " + unAbbreviatedLength + " bytes unabbreviated" +
+         " to " + abbreviatedLength + " bytes abbreviated, for a total of " + bytesSaved +
+         " bytes saved!";
+}
+
+function abbreviate(node) {
+  /* Remove all properties from a node dictionary which can easily be reconstructed
+
+  Omits the following properties:
+  - node.id, which is inferred from `label` through `getNeutralId`
+  - node.color, which is inferred from `level` through `getColor`
+  - node.value, which is inferred from `startpages` (included separately)
+  - node.x, which doesn't matter at all for reconstruction
+  - node.y, which also doesn't matter at all
+
+  This leaves us with:
+  - node.label, which is used to reconstruct node.id
+  - node.level, which is used to reconstruct node.color
+  - node.parent, which is used to reconstruct the network's edges */
+
+  var newnode = {label: node.label,
+                 level: node.level,
+                 parent: node.parent,};
+  return node;
+}
+
+function networkToJson() {
+  // Concisely JSON-ize the data needed to quickly reconstruct the network
+
+  var out = {};
+
+  // Store nodes
+  var data = nodes._data; // Retreive an object representing nodes data
+  var vals = Object.keys(data).map(function(k){return data[k];});
+  var abbv = vals.map(function(v){return abbreviate(v);}); // Process it
+  out.nodes = abbv; // Store it
+
+  // Store startpages
+  out.startpages = startpages;
+
+  return JSON.stringify(out);
+}
+
+function networkFromJson() {
+  return;
+}