make the entire runtime run in node

Working towards numbas/numbas-lti-provider#110.

This changes the script queueing stuff to add module.exports from each
script to the `window` and `global` objects, if they exist.

Now the entire Numbas runtime can run unmodified in node.js, if the
`browser-env` package is loaded first and you set `Numbas.display =
null` before trying to load an exam.

This commit also changes the compiler so it adds a file
'numbas-manifest.json' to the package, with the Numbas version and a
dict of features that could be added to over time, so a tool can
automatically work out if a package supports the feature it wants
without trying to run the JS.

bin/numbas.py

@@ -33,6 +33,9 @@
 import jinja2
 
 
+NUMBAS_VERSION = '5.2'
+
+
 namespaces = {
     '': 'http://www.imsglobal.org/xsd/imscp_v1p1',
     'xsi': 'http://www.w3.org/2001/XMLSchema-instance',
@@ -152,6 +155,8 @@ def compile(self):
 
         self.add_source()
 
+        self.add_manifest()
+
         if self.options.scorm:
             self.add_scorm()
 
@@ -403,6 +408,20 @@ def add_source(self):
         """
         self.files[os.path.join('.','source.exam')] = io.StringIO(self.options.source)
 
+    def add_manifest(self):
+        features = {
+            'run_headless': True,
+            'scorm': self.options.scorm,
+            'has_index_html': self.options.expect_index_html,
+        }
+        manifest = {
+            'Numbas_version': NUMBAS_VERSION,
+            'source_url': self.options.source_url,
+            'locale': self.options.locale,
+            'features': features,
+        }
+        self.files[os.path.join('.','numbas-manifest.json')] = io.StringIO(json.dumps(manifest))
+
     def minify(self):
         """
             Minify all javascript files in the package

runtime/scripts/es6-promise/es6-promise.js

@@ -1,4 +1,7 @@
 Numbas.queueScript('es6-promise',[],function(module) {
+    if(typeof Promise!=='undefined') {
+        return;
+    }
 /*!
  * @overview es6-promise - a tiny implementation of Promises/A+.
  * @copyright Copyright (c) 2014 Yehuda Katz, Tom Dale, Stefan Penner and contributors (Conversion to ES6 API by Jake Archibald)
@@ -793,4 +796,4 @@ Numbas.queueScript('es6-promise',[],function(module) {
     }
     lib$es6$promise$polyfill$$default();
 }).call(this);
-});
+});

runtime/scripts/localisation.js

@@ -1,4 +1,4 @@
-Numbas.queueScript('localisation',['i18next','localisation-resources'],function() {
+Numbas.queueScript('localisation',['i18next','localisation-resources'],function(module) {
     i18next.init({
         lng: Numbas.locale.preferred_locale,
         lowerCaseLng: true,
@@ -14,5 +14,5 @@ Numbas.queueScript('localisation',['i18next','localisation-resources'],function(
         },
         resources: Numbas.locale.resources
     });
-    window.R = function(){{ return i18next.t.apply(i18next,arguments) }};
-});
+    module.exports.R = function(){{ return i18next.t.apply(i18next,arguments) }};
+});

runtime/scripts/numbas.js

@@ -15,16 +15,16 @@ Copyright 2011-14 Newcastle University
  * Creates the global {@link Numbas} object, inside which everything else is stored, so as not to conflict with anything else that might be running in the page.
  */
 (function() {
-try {
-    window;
-} catch(e) {
-    try {
-        global.window = global;
-        global.alert = function(m) { console.error(m); }
-    } catch(e) {
+    if(typeof window=='undefined') {
+        if(typeof global!=='undefined') {
+            window = global.window = global;
+            global.alert = function(m) { console.error(m); }
+        }
+    }
+    if(!window.Numbas) { window.Numbas = {} }
+    if(typeof global!=='undefined') {
+        global.Numbas = window.Numbas;
     }
-}
-if(!window.Numbas) { window.Numbas = {} }
 /** @namespace Numbas */
 /** Extensions should add objects to this so they can be accessed */
 Numbas.extensions = {};
@@ -131,7 +131,14 @@ RequireScript.prototype = {
             var dependencies_executed = this.fdeps.every(function(r){ return scriptreqs[r].executed; });
             if(dependencies_executed) {
                 if(this.callback) {
-                    this.callback.apply(window,[{exports:window}]);
+                    var module = { exports: {} };
+                    this.callback.apply(window,[module]);
+                    for(var x in module.exports) {
+                        window[x] = module.exports[x];
+                        if(typeof global!=='undefined') {
+                            global[x] = module.exports[x];
+                        }
+                    }
                 }
                 this.executed = true;
                 this.backdeps.forEach(function(r) {

runtime/scripts/question.js

@@ -522,7 +522,7 @@ Question.prototype = /** @lends Numbas.Question.prototype */
                 switch(q.partsMode) {
                     case 'all':
                         parts.forEach(function(pd,i) {
-                            var p = Numbas.createPartFromJSON(pd, 'p'+i, q, q.store);
+                            var p = Numbas.createPartFromJSON(pd, 'p'+i, q, null, q.store);
                             q.addPart(p,i);
                         });
                         break;

themes/default/files/scripts/mathjax.js

@@ -1,4 +1,7 @@
 Numbas.queueScript('mathjax-hooks',['display-base','jme','jme-display'],function() {
+    if(typeof MathJax=='undefined') {
+        return;
+    }
     var jme = Numbas.jme;
     Numbas.display.MathJaxQueue = MathJax.Hub.queue;
     MathJax.Hub.Register.MessageHook("Math Processing Error",function(message){