Standardize how JS XModules are instantiated

common/static/coffee/src/xmodule.coffee

@@ -0,0 +1,30 @@
+@XModule =
+    ###
+    Load a single module (either an edit module or a display module)
+    from the supplied element, which should have a data-type attribute
+    specifying the class to load
+    ###
+    loadModule: (element) ->
+        moduleType = $(element).data('type')
+        if moduleType == 'None'
+            return
+
+        try
+            new window[moduleType](element)
+        catch error
+            console.error "Unable to load #{moduleType}: #{error.message}" if console
+
+    ###
+    Load all modules on the page of the specified type.
+    If container is provided, only load modules inside that element
+    Type is one of 'display' or 'edit'
+    ###
+    loadModules: (type, container) ->
+        selector = ".xmodule_#{type}"
+
+        if container?
+            modules = $(container).find(selector)
+        else
+            modules = $(selector)
+
+        modules.each (idx, element) -> XModule.loadModule element