From 24d89330234368fb4bdf488e393436a5942e5089 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Mon, 3 Aug 2020 12:11:46 +0200
Subject: [PATCH] Use a `DocumentFragment` when building the attachmentsView in
 `PDFAttachmentViewer.render`

This approach is already used in other parts of the code-base, see e.g. `PDFOutlineViewer`, and has the advantage of only invalidating the DOM once rather than for every attachment item.
---
 web/pdf_attachment_viewer.js | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/web/pdf_attachment_viewer.js b/web/pdf_attachment_viewer.js
index 529c77121..2210dfde4 100644
--- a/web/pdf_attachment_viewer.js
+++ b/web/pdf_attachment_viewer.js
@@ -129,23 +129,22 @@ class PDFAttachmentViewer {
    * @param {PDFAttachmentViewerRenderParameters} params
    */
   render({ attachments, keepRenderedCapability = false }) {
-    let attachmentsCount = 0;
-
     if (this.attachments) {
       this.reset(keepRenderedCapability === true);
     }
     this.attachments = attachments || null;
 
     if (!attachments) {
-      this._dispatchEvent(attachmentsCount);
+      this._dispatchEvent(/* attachmentsCount = */ 0);
       return;
     }
 
     const names = Object.keys(attachments).sort(function (a, b) {
       return a.toLowerCase().localeCompare(b.toLowerCase());
     });
-    attachmentsCount = names.length;
+    const attachmentsCount = names.length;
 
+    const fragment = document.createDocumentFragment();
     for (let i = 0; i < attachmentsCount; i++) {
       const item = attachments[names[i]];
       const filename = removeNullCharacters(getFilenameFromUrl(item.filename));
@@ -164,8 +163,9 @@ class PDFAttachmentViewer {
       }
 
       div.appendChild(button);
-      this.container.appendChild(div);
+      fragment.appendChild(div);
     }
+    this.container.appendChild(fragment);
 
     this._dispatchEvent(attachmentsCount);
   }