From 4886a7cf69e8fe4c92242a730e35889cde8592d7 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Tue, 17 Nov 2020 13:37:21 +0100
Subject: [PATCH 1/2] Skip `Promise.all` in
 `PDFViewerApplication._parseHashParameters` unless actually necessary

Given that only two debugging hash parameters (i.e. `disableWorker` and `pdfBug`) will make this method asynchronous, we can avoid what's most of the time is an unnecessary `Promise.all` invocation.
---
 web/app.js | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/web/app.js b/web/app.js
index d07853f6c..2ecc49e4c 100644
--- a/web/app.js
+++ b/web/app.js
@@ -385,6 +385,9 @@ const PDFViewerApplication = {
       AppOptions.set("locale", hashParams.locale);
     }
 
+    if (waitOn.length === 0) {
+      return undefined;
+    }
     return Promise.all(waitOn).catch(reason => {
       console.error(`_parseHashParameters: "${reason.message}".`);
     });

From cc861c34e9abe3044835ac5cf26e8028bb6e5e03 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Tue, 17 Nov 2020 13:44:15 +0100
Subject: [PATCH 2/2] Add an `AppOptions.setAll` method, and use it in
 `PDFViewerApplication._readPreferences`

Given that it's generally faster to call *one* function and have it loop through an object, rather than looping through an object and calling a function for every iteration, this patch will reduce the total time spent in `PDFViewerApplication._readPreferences` ever so slightly.
Also, over time we've been adding more and more preferences, rather than removing them, so using the new `AppOptions.setAll` method should be generally beneficial as well.

While the effect of these changes is quite small, it does reduces the time it takes for the preferences to be fully initialized. Given the amount of asynchronous code during viewer initialization, every bit of time that we can save should thus help.
Especially considering the recently added `viewerCssTheme` preference, which needs to be read very early to reduce the risk of the viewer UI "flashing" visibly as the theme changes, I figured that a couple of small patches reducing the time spend reading preferences cannot hurt.
---
 web/app.js         | 7 ++-----
 web/app_options.js | 6 ++++++
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/web/app.js b/web/app.js
index 2ecc49e4c..91384891b 100644
--- a/web/app.js
+++ b/web/app.js
@@ -305,12 +305,9 @@ const PDFViewerApplication = {
       return;
     }
     try {
-      const prefs = await this.preferences.getAll();
-      for (const name in prefs) {
-        AppOptions.set(name, prefs[name]);
-      }
+      AppOptions.setAll(await this.preferences.getAll());
     } catch (reason) {
-      console.error(`_readPreferences: "${reason.message}".`);
+      console.error(`_readPreferences: "${reason?.message}".`);
     }
   },
 
diff --git a/web/app_options.js b/web/app_options.js
index e4931997b..8a83bd42e 100644
--- a/web/app_options.js
+++ b/web/app_options.js
@@ -314,6 +314,12 @@ class AppOptions {
     userOptions[name] = value;
   }
 
+  static setAll(options) {
+    for (const name in options) {
+      userOptions[name] = options[name];
+    }
+  }
+
   static remove(name) {
     delete userOptions[name];
   }