Validate external Babel browser entrypoint (#6)

Co-authored-by: daggerok <daggerok@users.noreply.github.com>

Author: daggerok

scripts/check-index.ts

@@ -1,31 +1,61 @@
 #!/usr/bin/env bun
 
-// Parse the browser's inline TypeScript before publishing. The deployed page
-// relies on Babel standalone at runtime, so a missing comma or other syntax
-// error would otherwise leave the catalog permanently on its loading state.
+// Parse the browser's TypeScript before publishing. The deployed page relies
+// on Babel standalone at runtime, so a missing comma or other syntax error
+// would otherwise leave the catalog permanently on its loading state.
 
 declare const Bun: {
   file(path: string): { text(): Promise<string> };
   Transpiler: new (options: { loader: string }) => { transform(source: string): string | Promise<string> };
 };
 
-type Match = RegExpExecArray & { 1: string };
+type BrowserScript = { inline: string } | { src: string };
 
+function attributeValue(attributes: string, name: string): string | null {
+  const match = new RegExp(`\\b${name}\\s*=\\s*(?:"([^"]*)"|'([^']*)'|([^\\s>]+))`, 'i').exec(attributes);
+  return match ? (match[1] ?? match[2] ?? match[3] ?? '') : null;
+}
+
+export function extractBrowserScript(html: string): BrowserScript {
+  const scripts = /<script\b([^>]*)>([\s\S]*?)<\/script>/gi;
+  let match: RegExpExecArray | null;
+  while ((match = scripts.exec(html))) {
+    const type = attributeValue(match[1], 'type');
+    if (type?.toLowerCase() !== 'text/babel') continue;
+    const src = attributeValue(match[1], 'src');
+    if (src) return { src };
+    if (match[2].trim()) return { inline: match[2] };
+  }
+  throw new Error('index.html: text/babel browser script not found');
+}
+
+// Keep the original helper for callers that specifically want an inline
+// script, while allowing the page to move its Babel entrypoint into a local
+// .tsx file without making this validation stale.
 export function extractInlineBrowserScript(html: string): string {
-  const match = /<script\s+type=["']text\/babel["'][^>]*>([\s\S]*?)<\/script>/i.exec(html) as Match | null;
-  if (!match || !match[1].trim()) throw new Error('index.html: inline text/babel script not found');
-  return match[1];
+  const script = extractBrowserScript(html);
+  if ('inline' in script) return script.inline;
+  throw new Error(`index.html: text/babel script is external (${script.src})`);
 }
 
-export async function parseInlineBrowserScript(source: string): Promise<string> {
+export async function parseBrowserScript(source: string): Promise<string> {
   const transformed = await new Bun.Transpiler({ loader: 'tsx' }).transform(source);
-  if (!transformed || typeof transformed !== 'string') throw new Error('index.html: inline script did not transpile');
+  if (!transformed || typeof transformed !== 'string') throw new Error('browser script did not transpile');
   return transformed;
 }
 
+// Backwards-compatible name for the inline-script parser used by the earlier
+// single-file layout.
+export const parseInlineBrowserScript = parseBrowserScript;
+
 if ((import.meta as { main?: boolean }).main) {
-  const html = await Bun.file(new URL('../index.html', import.meta.url).pathname).text();
-  const source = extractInlineBrowserScript(html);
-  const transformed = await parseInlineBrowserScript(source);
-  console.log(`index.html inline script parses (${source.length.toLocaleString()} source chars, ${transformed.length.toLocaleString()} transpiled chars)`);
+  const indexUrl = new URL('../index.html', import.meta.url);
+  const html = await Bun.file(indexUrl.pathname).text();
+  const script = extractBrowserScript(html);
+  const sourcePath = 'src' in script ? new URL(script.src, indexUrl) : indexUrl;
+  if (sourcePath.protocol !== 'file:') throw new Error(`browser script must be local: ${sourcePath.href}`);
+  const source = 'inline' in script ? script.inline : await Bun.file(sourcePath.pathname).text();
+  const transformed = await parseBrowserScript(source);
+  const label = 'src' in script ? script.src : 'index.html inline script';
+  console.log(`${label} parses (${source.length.toLocaleString()} source chars, ${transformed.length.toLocaleString()} transpiled chars)`);
 }