Merge pull request #4910 from mlkwaqas/waqas/bld1199-mathjax-error

MaxJax error while submitting answer

common/static/js/capa/spec/formula_equation_preview_spec.js

@@ -62,7 +62,17 @@ describe("Formula Equation Preview", function () {
         window.MathJax = {Hub: {}};
         MathJax.Hub.getAllJax = jasmine.createSpy('MathJax.Hub.getAllJax')
             .andReturn([this.jax]);
-        MathJax.Hub.Queue = jasmine.createSpy('MathJax.Hub.Queue');
+        MathJax.Hub.Queue = function (callback) {
+            if (typeof (callback) == 'function') {
+                callback();
+            }
+        }
+        spyOn(MathJax.Hub, 'Queue').andCallThrough()
+        MathJax.Hub.Startup = jasmine.createSpy('MathJax.Hub.Startup');
+        MathJax.Hub.Startup.signal = jasmine.createSpy('MathJax.Hub.Startup.signal');
+        MathJax.Hub.Startup.signal.Interest = function (callback) {
+            callback('End');
+        }
     });
 
     it('(the test) is able to swap out the behavior of $', function () {
@@ -245,7 +255,7 @@ describe("Formula Equation Preview", function () {
 
                 // Cannot find MathJax.
                 MathJax.Hub.getAllJax.andReturn([]);
-                spyOn(console, 'warn');
+                spyOn(console, 'log');
 
                 callback({
                     preview: 'THE_FORMULA',
@@ -253,7 +263,7 @@ describe("Formula Equation Preview", function () {
                 });
 
                 // Tests.
-                expect(console.warn).toHaveBeenCalled();
+                expect(console.log).toHaveBeenCalled();
 
                 // We should look in the preview div for the MathJax.
                 var previewElement = $("#input_THE_ID_preview")[0];

common/static/js/capa/src/formula_equation_preview.js

@@ -127,27 +127,31 @@ formulaEquationPreview.enable = function () {
         }
 
         function display(latex) {
-            // Load jax if it failed before.
+            MathJax.Hub.Startup.signal.Interest(function (message) {
+                if(message === "End") {
                     var previewElement = inputData.$preview[0];
-            if (!inputData.jax) {
+                    MathJax.Hub.Queue(function () {
                         inputData.jax = MathJax.Hub.getAllJax(previewElement)[0];
-            }
+                    });
 
-            // MathJax might not be loaded yet (still).
+                    MathJax.Hub.Queue(function () {
+                        // Check if MathJax is loaded
                         if (inputData.jax) {
                             // Set the text as the latex code, and then update the MathJax.
                             MathJax.Hub.Queue(
                                 ['Text', inputData.jax, latex],
                                 ['Reprocess', inputData.jax]
                             );
-            }
-            else if (latex) {
-                console.warn("[FormulaEquationInput] Oops no mathjax for ", latex);
+                        } else if (latex) {
+                            console.log("[FormulaEquationInput] Oops no mathjax for ", latex);
                             // Fall back to modifying the actual element.
                             var textNode = previewElement.childNodes[0];
                             textNode.data = "\\[" + latex + "\\]";
                             MathJax.Hub.Queue(["Typeset", MathJax.Hub, previewElement]);
                         }
+                    });
+                }
+            });
         }
 
         if (response.error) {