feat: extract summary from MDN comments for better documentation

Author: Bashamega

src/build/emitter.ts

@@ -12,6 +12,7 @@ import {
   arrayBufferViewTypes,
 } from "./helpers.js";
 import { collectLegacyNamespaceTypes } from "./legacy-namespace.js";
+import { extractSummaryFromFile } from "./mdn-comments.js";
 
 /// Decide which members of a function to emit
 enum EmitScope {
@@ -906,7 +907,10 @@ export function emitWebIdl(
       comments.push("Available only in secure contexts.");
     }
     if (entity.mdnUrl) {
-      if (comments.length > 0) comments.push("");
+      if (comments.length == 0) {
+        comments.push(extractSummaryFromFile(entity.mdnUrl));
+      }
+      comments.push("");
       comments.push(`[MDN Reference](${entity.mdnUrl})`);
     }
 

src/build/mdn-comments.ts

@@ -107,3 +107,25 @@ export function generateDescriptions(): Record<string, string> {
 
   return {};
 }
+
+export function extractSummaryFromFile(url: string): string {
+  const relativePath = url
+    .replace("https://developer.mozilla.org/docs/", "")
+    .toLowerCase();
+
+  const filePath = new URL(
+    `../../inputfiles/mdn/files/en-us/${relativePath}/index.md`,
+    import.meta.url,
+  );
+
+  try {
+    const content = fs.readFileSync(filePath, "utf-8");
+    return extractSummary(content);
+  } catch (error) {
+    console.error(
+      `Failed to read or extract summary from: ${filePath.href}`,
+      error,
+    );
+    return "";
+  }
+}