feat(#148): add support for Math expression

public/index.html

@@ -56,8 +56,11 @@
     <script src="/script/external/popper.min.js"></script>
     <script src="/script/external/bootstrap.min.js"></script>
 
+    <!-- PDF -->
     <script src="/script/external/pdf.compat.js"></script>
     <script src="/script/external/pdf.js"></script>
+
+    <!-- Code -->
     <script src="/script/external/ace/ace.js"></script>
     <script src="/script/external/ui-ace.min.js"></script>
     <script src="/script/langColors.js"></script>

public/script/app.js

@@ -259,7 +259,7 @@ angular
         },
         link: function (scope, elem, attrs) {
           function update() {
-            elem.html(marked(scope.content, { baseUrl: $location.url() }));
+            elem.html(renderMD(scope.content, $location.url()));
           }
           scope.$watch(attrs.terms, update);
           scope.$watch("terms", update);
@@ -1320,7 +1320,7 @@ angular
         }
 
         $scope.anonymize_readme = content;
-        const html = marked($scope.anonymize_readme);
+        const html = renderMD($scope.anonymize_readme, $location.url());
         $scope.html_readme = $sce.trustAsHtml(html);
         setTimeout(Prism.highlightAll, 150);
       }
@@ -1642,9 +1642,8 @@ angular
               }
 
               if ($scope.type == "md") {
-                const md = contentAbs2Relative(res.data);
                 $scope.content = $sce.trustAsHtml(
-                  marked(md, { baseUrl: $location.url() })
+                  renderMD(res.data, $location.url())
                 );
                 $scope.type = "html";
               }

public/script/utils.js

@@ -109,3 +109,44 @@ function parseGithubUrl(url) {
     throw "Invalid url";
   }
 }
+
+function renderMD(md, baseUrl) {
+  md = contentAbs2Relative(md);
+  const renderer = new marked.Renderer();
+  // katex
+  function mathsExpression(expr) {
+    if (expr.match(/^\$\$[\s\S]*\$\$$/)) {
+      expr = expr.substr(2, expr.length - 4);
+      return katex.renderToString(expr, { displayMode: true });
+    } else if (expr.match(/^\$[\s\S]*\$$/)) {
+      expr = expr.substr(1, expr.length - 2);
+      return katex.renderToString(expr, { isplayMode: false });
+    }
+  }
+
+  const rendererCode = renderer.code;
+  renderer.code = function (code, lang, escaped) {
+    if (!lang) {
+      const math = mathsExpression(code);
+      if (math) {
+        return math;
+      }
+    }
+    // call default renderer
+    return rendererCode.call(this, code, lang, escaped);
+
+    // return rendererCode(code, lang, escaped);
+  };
+
+  const rendererCodespan = renderer.codespan;
+  renderer.codespan = function (text) {
+    const math = mathsExpression(text);
+
+    if (math) {
+      return math;
+    }
+
+    return rendererCodespan(text);
+  };
+  return marked.parse(md, { baseUrl, renderer });
+}