Adding more documentation

src/js/parser/javascript/parser.js

@@ -1,3 +1,7 @@
+// Sets up the parser generated by canopy to use the
+// [Node](./javascript/node.html) subclasses in the generated tree. This is all
+// a bit of a hack that is dependent on how canopy creates nodes in its parse
+// tree.
 import parser from './grammar.peg';
 
 import Node from './node.js';
@@ -18,7 +22,15 @@ import RepeatOptional from './repeat_optional.js';
 import RepeatRequired from './repeat_required.js';
 import RepeatSpec from './repeat_spec.js';
 
+// Canopy creates an instance of SyntaxNode for each element in the tree, then
+// adds any necessary fields to that instance. In this case, we're replacing
+// the default class with the Node class.
 parser.Parser.SyntaxNode      = Node;
+
+// Once the SyntaxNode instance is created, the specific node type object is
+// overlayed onto it. This causes the module attribute on the Node to be set,
+// which updates the Node instance into the more specific "subclass" that is
+// used for rendering.
 parser.Parser.Root            = { module: Root };
 parser.Parser.Regexp          = { module: Regexp };
 parser.Parser.Match           = { module: Match };

src/js/parser/javascript/parser_state.js

@@ -1,13 +1,23 @@
+// State tracking for an in-progress parse and render.
 export default class ParserState {
+  // - __progress__ - DOM node to update to indicate completion progress.
   constructor(progress) {
+    // Tracks the number of capture groups in the expression.
     this.groupCounter = 1;
+    // Cancels the in-progress render when set to true.
     this.cancelRender = false;
+    // Warnings that have been generated while rendering.
     this.warnings = [];
+
+    // Used to display the progress indicator
     this._renderCounter = 0;
     this._maxCounter = 0;
     this._progress = progress;
   }
 
+  // Counts the number of in-progress rendering steps. As the counter goes up,
+  // a maximum value is also tracked. The maximum value and current render
+  // counter are used to calculate the completion process.
   get renderCounter() {
     return this._renderCounter;
   }