fix(mathjax): stop refreshMath binding on formula equation inputs

Author: navinkarkera

xblocks_contrib/problem/assets/spec/display_spec.js

@@ -91,6 +91,23 @@ data-url='/problem/quiz/'> \
     it("bind the math input", function () {
       expect($("input.math")).toHandleWith("keyup", this.problem.refreshMath);
     });
+
+    it("does not bind refreshMath to formula equation inputs", function () {
+      // Formula-equation inputs are exclusively managed by formula_equation_preview.js.
+      $.ajax.and.callFake(function (settings) {
+        if (settings.url.match(/.+\/problem_get$/)) {
+          settings.success({
+            html: readFixtures("problem_content.html") +
+              '<section class="formulaequationinput"><input type="text" id="input_formula_1" />' +
+              '<div id="input_formula_1_preview" class="equation"></div></section>',
+          });
+        }
+      });
+      this.problem = new Problem(mockRuntime, $(".xblock-student_view"));
+      MathJax.typesetClear.calls.reset();
+      $(".formulaequationinput input").trigger("keyup");
+      expect(MathJax.typesetClear).not.toHaveBeenCalled();
+    });
   });
 
   describe("bind_with_custom_input_id", function () {

xblocks_contrib/problem/assets/static/js/display.js

@@ -119,9 +119,10 @@ Problem.prototype.bind = function () {
     this.submitAnswersAndSubmitButton(true);
   }
   Collapsible.setCollapsibles(this.el);
-  this.$("input.math, .formulaequationinput input").keyup(this.refreshMath);
+  // Formula equation inputs use formula_equation_preview.js to manage their server-rendered preview.
+  this.$("input.math").keyup(this.refreshMath);
   if (isMathJaxTypesetReady()) {
-    this.$("input.math, .formulaequationinput input").each(function (index, element) {
+    this.$("input.math").each(function (index, element) {
       return MathJax.startup.promise.then(() => that.refreshMath(null, element));
     });
   }