MathJax preprocessor comes from external plugin

common/lib/capa/capa/capa_problem.py

@@ -382,10 +382,10 @@ class LoncapaProblem(object):
         original_path = sys.path
 
         for script in scripts:
-
             sys.path = original_path + self._extract_system_path(script)
 
             stype = script.get('type')
+            
             if stype:
                 if 'javascript' in stype:
                     continue    # skip javascript

common/lib/capa/capa/templates/textinput_dynamath.html

 ###
-### version of textline.html which does dynammic math
+### version of textline.html which does dynamic math
 ###
-<section class="text-input-dynamath">
+<section class="text-input-dynamath textinputdynamath capa_inputtype" id="inputtype_${id}">
     % if state == 'unsubmitted':
     <div class="unanswered" id="status_${id}">
     % elif state == 'correct':
@@ -20,7 +20,7 @@
       	    style="display:none;"
        % endif
       />
-
+      <div class="script_placeholder" data-src="/static/js/mathjax_preprocessor_for_6002x.js"/>
       <p class="status">
         % if state == 'unsubmitted':
         unanswered

common/lib/xmodule/xmodule/js/src/capa/display.coffee

@@ -7,11 +7,6 @@ class @Problem
     @url = @el.data('url')
     @render()
 
-    # TODO: Each course should be able to customize the MathJax preprocessor
-    #       through a generic plug-in
-    if (@id).search('6.002x') >= 0
-      @mathjax_preprocessor = @mathjax_preprocessor_for_6002x 
-
   $: (selector) ->
     $(selector, @el)
 
@@ -305,47 +300,12 @@ class @Problem
 
     if jax = MathJax.Hub.getAllJax(target)[0]
       eqn = $(element).val()
-      if @mathjax_preprocessor
-        eqn = @mathjax_preprocessor(eqn)
+      if window.mathjax_preprocessor
+        eqn = window.mathjax_preprocessor(eqn)
 
       MathJax.Hub.Queue ['Text', jax, eqn],
         [@updateMathML, jax, element]
  
-  # TODO: The 6.002x preprocessor should not be baked into capa/display.coffee, but should be a plug-in 
-  mathjax_preprocessor_for_6002x: (eqn) ->
-    ###
-    Translate 6.002x conventions for subscripts to standard Latex, e.g.
-      'R3'  --> 'R_{3}'
-      'vGS' --> 'v_{GS}'
-      'K/2*(vIN-VT)^2' --> 'K/2*(v_{IN}-V_{T})^2'
-
-    ... and also escape specific 6.002x-related keywords from MathJax,
-        such as 'in' (parsed by MathJax as the set symbol)
-    ###
-    
-    # Default keywords are taken from capa/calc.py
-    default_keywords = ['sin', 'cos', 'tan', 'sqrt', 'log10', 'log2', 'ln', 'arccos', 'arcsin', 'arctan', 'abs', 'pi']
-
-    # Escape keywords are strings that have special meaning in 6.002x that should not be processed by Jax
-    escape_keywords = ['in']
-
-    # First, perform subscript insertion, but watch out for keywords
-    replace_subscript = (match) ->
-      if match in default_keywords or match in escape_keywords
-        return match
-      else
-        return match[0] + '_{' + match.substr(1) + '}'
-    eqn = eqn.replace(/[A-Za-z]\w+/g, replace_subscript)
-
-    # Second, escape 6.002x-specific keywords from MathJax
-    replace_escape_keyword = (match) -> 
-      return '"' + match + '"' # Force MathJax plain text
-    for escape_keyword in escape_keywords
-      escape_keyword_patt = RegExp('\\b'+escape_keyword+'\\b')
-      eqn = eqn.replace(escape_keyword_patt, replace_escape_keyword)
-
-    return eqn
-
   updateMathML: (jax, element) =>
     try
       $("##{element.id}_dynamath").val(jax.root.toMathML '')
@@ -361,6 +321,10 @@ class @Problem
     @answers = @inputs.serialize()
 
   inputtypeSetupMethods:
+
+    textinputdynamath: (element) =>
+      @mathjax_preprocessor = window.mathjax_preprocessor 
+
     javascriptinput: (element) =>
 
       data = $(element).find(".javascriptinput_data")