Adding documentation to main.js

src/js/main.js

@@ -1,13 +1,26 @@
+// This file contains code to start up pages on the site, and other code that
+// is not directly related to parsing and display of regular expressions.
+//
+// Since the code in this is executed immediately, it is all but impossible to
+// test. Therefore, this code is kept as simple as possible to reduce the need
+// to run it through automated tests.
+
 import util from './util.js';
 import Regexper from './regexper.js';
 import Parser from './parser/javascript.js';
 import _ from 'lodash';
 
+// Add a dummy version of `_gaq` (the Google Analytics global object). This
+// dummy object will log out tracking commands that would otherwise be sent to
+// Google Analytics.
 window._gaq = (typeof _gaq !== 'undefined') ? _gaq : {
   push: console.debug.bind(console)
 };
 
 (function() {
+  // Global error handler that will send unhandled JavaScript exceptions and
+  // stack-traces to Google Analytics. This data can be used to find errors in
+  // code that were not found during testing.
   window.addEventListener('error', function(error) {
     if (error.lineno !== 0) {
       _gaq.push([
@@ -28,6 +41,8 @@ window._gaq = (typeof _gaq !== 'undefined') ? _gaq : {
     }
   });
 
+  // Initialize the main page of the site. Functionality is kept in the
+  // [Regexper class](./regexper.html).
   if (document.body.querySelector('#content .application')) {
     var regexper = new Regexper(document.body);
 
@@ -38,6 +53,9 @@ window._gaq = (typeof _gaq !== 'undefined') ? _gaq : {
     });
   }
 
+  // Initialize other pages on the site (specifically the documentation page).
+  // Any element with a `data-expr` attribute will contain a rendering of the
+  // provided regular expression.
   _.each(document.querySelectorAll('[data-expr]'), element => {
     new Parser(element, { keepContent: true })
       .parse(element.getAttribute('data-expr'))