From 5107259176152c9217cafe21e3454f480598fd50 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Tue, 29 Sep 2020 15:35:58 +0200
Subject: [PATCH 1/2] Update `escodegen` to version 2.0

This release contains support for additional modern ECMAScript features, such as e.g. the nullish coalescing operator `??` and the optional chaining operator `?.`.
---
 package-lock.json | 16 ++++++++++++----
 package.json      |  2 +-
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/package-lock.json b/package-lock.json
index 1ac4854ba0416..942e3c0e666d4 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -4468,16 +4468,24 @@
       "dev": true
     },
     "escodegen": {
-      "version": "1.14.3",
-      "resolved": "https://registry.npmjs.org/escodegen/-/escodegen-1.14.3.tgz",
-      "integrity": "sha512-qFcX0XJkdg+PB3xjZZG/wKSuT1PnQWx57+TVSjIMmILd2yC/6ByYElPwJnslDsuWuSAp4AwJGumarAAmJch5Kw==",
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/escodegen/-/escodegen-2.0.0.tgz",
+      "integrity": "sha512-mmHKys/C8BFUGI+MAWNcSYoORYLMdPzjrknd2Vc+bUsjN5bXcr8EhrNB+UTqfL1y3I9c4fw2ihgtMPQLBRiQxw==",
       "dev": true,
       "requires": {
         "esprima": "^4.0.1",
-        "estraverse": "^4.2.0",
+        "estraverse": "^5.2.0",
         "esutils": "^2.0.2",
         "optionator": "^0.8.1",
         "source-map": "~0.6.1"
+      },
+      "dependencies": {
+        "estraverse": {
+          "version": "5.2.0",
+          "resolved": "https://registry.npmjs.org/estraverse/-/estraverse-5.2.0.tgz",
+          "integrity": "sha512-BxbNGGNm0RyRYvUdHpIwv9IWzeM9XClbOxwoATuFdOE7ZE6wHL+HQ5T8hoPM+zHvmKzzsEqhgy0GrQ5X13afiQ==",
+          "dev": true
+        }
       }
     },
     "eslint": {
diff --git a/package.json b/package.json
index 7734b98aed70d..8f8d56235d34e 100644
--- a/package.json
+++ b/package.json
@@ -15,7 +15,7 @@
     "core-js": "^3.6.5",
     "cross-env": "^7.0.2",
     "es-module-shims": "^0.4.7",
-    "escodegen": "^1.14.3",
+    "escodegen": "^2.0.0",
     "eslint": "^7.9.0",
     "eslint-config-prettier": "^6.11.0",
     "eslint-plugin-fetch-options": "^0.0.5",

From db4cefbac3e51f4300053cd293bba76ff20ab494 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Tue, 29 Sep 2020 15:45:05 +0200
Subject: [PATCH 2/2] Add basic support for the optional chaining operator `?.`

For now we need to use a Babel-plugin, since part of our build system doesn't support this fully (e.g. Babel-loader, Webpack 4.x, and SystemJS).

While the `?.` operator will thus always be transpiled by Babel, even in modern builds, simply supporting it for development purposes seems like a step in the right direction.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Optional_chaining
---
 gulpfile.js  | 6 ++++++
 package.json | 1 +
 web/app.js   | 2 +-
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/gulpfile.js b/gulpfile.js
index 4316751361842..e197e715553c5 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -224,6 +224,12 @@ function createWebpackConfig(defines, output) {
                   loose: true,
                 },
               ],
+              [
+                "@babel/plugin-proposal-optional-chaining",
+                {
+                  loose: true,
+                },
+              ],
               "@babel/plugin-transform-modules-commonjs",
               [
                 "@babel/plugin-transform-runtime",
diff --git a/package.json b/package.json
index 8f8d56235d34e..54ab7c993d915 100644
--- a/package.json
+++ b/package.json
@@ -4,6 +4,7 @@
   "devDependencies": {
     "@babel/core": "^7.11.6",
     "@babel/plugin-proposal-nullish-coalescing-operator": "^7.10.4",
+    "@babel/plugin-proposal-optional-chaining": "^7.11.0",
     "@babel/plugin-transform-modules-commonjs": "^7.10.4",
     "@babel/plugin-transform-runtime": "^7.11.5",
     "@babel/preset-env": "^7.11.5",
diff --git a/web/app.js b/web/app.js
index fa9070834996e..252fdbc074bc0 100644
--- a/web/app.js
+++ b/web/app.js
@@ -846,7 +846,7 @@ const PDFViewerApplication = {
           return undefined; // Ignore errors for previously opened PDF files.
         }
 
-        const message = exception && exception.message;
+        const message = exception?.message;
         let loadingErrorMessage;
         if (exception instanceof InvalidPDFException) {
           // change error message also for other builds