perf: skip unused scripts in pdf mode (#9366)

Author: yufeih

src/Docfx.App/PdfBuilder.cs

@@ -133,6 +133,8 @@ static async Task CreatePdf(IBrowser browser, ProgressTask task, Uri outlineUrl,
         var pageNumber = 1;
         var nextPageNumber = 1;
 
+        var page = await browser.NewPageAsync(new() { UserAgent = "docfx/pdf" });
+
         // Make progress at 99% before merge PDF
         task.MaxValue = pages.Length + (pages.Length / 99.0);
         foreach (var (url, node) in pages)
@@ -158,14 +160,14 @@ static async Task CreatePdf(IBrowser browser, ProgressTask task, Uri outlineUrl,
 
         async Task<byte[]> CapturePdf(Uri url, int startPageNumber)
         {
-            var page = await browser.NewPageAsync();
             var response = await page.GotoAsync(url.ToString());
             if (response is null || !response.Ok)
                 throw new InvalidOperationException($"Failed to build PDF page [{response?.Status}]: {url}");
 
             await page.AddScriptTagAsync(new() { Content = EnsureHeadingAnchorScript });
             await page.AddScriptTagAsync(new() { Content = InsertHiddenPageScript(startPageNumber - 1) });
-            await page.WaitForLoadStateAsync(LoadState.NetworkIdle);
+            await page.WaitForLoadStateAsync(LoadState.DOMContentLoaded);
+            await page.WaitForFunctionAsync("!window.docfx || window.docfx.ready");
             var bytes = await page.PdfAsync(new()
             {
                 HeaderTemplate = "<span></span>",

templates/modern/src/docfx.ts

@@ -25,15 +25,22 @@ declare global {
 async function init() {
   window.docfx = window.docfx || {}
 
-  initTheme()
-
-  await Promise.all([
-    enableSearch(),
-    renderInThisArticle(),
-    renderMarkdown(),
-    renderNav(),
-    highlight()
-  ])
+  const pdfmode = navigator.userAgent.indexOf('docfx/pdf') >= 0
+  if (pdfmode) {
+    await Promise.all([
+      renderMarkdown(),
+      highlight()
+    ])
+  } else {
+    await Promise.all([
+      initTheme(),
+      enableSearch(),
+      renderInThisArticle(),
+      renderMarkdown(),
+      renderNav(),
+      highlight()
+    ])
+  }
 
   window.docfx.ready = true