Add site processor

The new processor appends the `docstring` class to code docstrings so that they can be styled.

_config.ts

@@ -59,4 +59,23 @@ site.use(toc({
 }));
 site.use(footnotes());
 
+site.process([".html"], (page) => {
+  // NOTE: This is a hack to append a class to JS doctrings so that we
+  // can style them. If only the Hightlight.js plugin could be configured
+  // to do this instead.
+  const codeCommentElements = page.document?.getElementsByClassName("hljs-comment");
+  if (codeCommentElements && codeCommentElements.length > 0) {
+    const docStringRegex = /^\/\*\*.*\*\/$/gsm;
+    const codeDocStringElements = codeCommentElements.filter((el) => {
+      const matchResult = el.innerText.match(docStringRegex);
+      return !!matchResult;
+    });
+    if (codeDocStringElements.length > 0) {
+      codeDocStringElements.forEach((el) => {
+        el.classList.add("docstring");
+      })
+    }
+  }
+});
+
 export default site;