Add context code support to exercises (optional)

Partial #52, fixes #49, fixes #46

theme/javascript/core/exercise.js

@@ -8,6 +8,7 @@ define([
     var prepareExercise = function($exercise) {
         var codeSolution = $exercise.find(".code-solution").text();
         var codeValidation = $exercise.find(".code-validation").text();
+        var codeContext = $exercise.find(".code-context").text();
 
         var editor = ace.edit($exercise.find(".editor").get(0));
         editor.setTheme("ace/theme/tomorrow");
@@ -20,7 +21,7 @@ define([
 
             analytic.track("exercise.submit");
 
-            execute("javascript", editor.getValue(), codeValidation, function(err, result) {
+            execute("javascript", editor.getValue(), codeValidation, codeContext, function(err, result) {
                 $exercise.toggleClass("return-error", err != null);
                 $exercise.toggleClass("return-success", err == null);
                 if (err) $exercise.find(".alert-danger").text(err.message || err);

theme/javascript/execute/javascript.js

@@ -2,6 +2,7 @@ define(function() {
     return {
         id: "javascript",
         assertCode: "function assert(condition, message) { \nif (!condition) { \n throw message || \"Assertion failed\"; \n } \n }\n",
-        REPL: JSREPL
+        REPL: JSREPL,
+        sep: ";\n",
     };
-});
+});

theme/javascript/utils/execute.js

@@ -71,13 +71,21 @@ define([
         repl.loadLanguage(lang.id, eventHandler);
     };
 
-    var execute = function(lang, solution, validation, callback) {
+    var execute = function(lang, solution, validation, context, callback) {
+        // Language data
+        var langd =  LANGUAGES[lang];
+
         // Check language is supported
-        if (!LANGUAGES[lang]) return callback(new Error("Language '"+lang+"' not available for execution"));
+        if (!langd) return callback(new Error("Language '"+lang+"' not available for execution"));
 
         // Validate with validation code
-        var code = [solution, LANGUAGES[lang].assertCode, validation].join(";\n");
-        evalJS(LANGUAGES[lang], code, function(err, res) {
+        var code = [
+            context,
+            solution,
+            langd.assertCode,
+            validation,
+        ].join(langd.sep);
+        evalJS(langd, code, function(err, res) {
             if(err) return callback(err);
 
             if (res.type == "error") callback(new Error(res.value));
@@ -86,4 +94,4 @@ define([
     };
 
     return execute;
-});
+});