From 8841c8c874ee7e9ad9df77f24f3d5c6fd6924cbd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timoth=C3=A9e=20Alby?= <timothee.alby@gmail.com>
Date: Thu, 28 Jul 2022 11:21:46 +0200
Subject: [PATCH] Merge pull request #9008 from
 overleaf/jpa-disable-pdf-caching-edge-legacy

[web] disable pdf caching feature in legacy Edge browser

GitOrigin-RevId: f57ca3385337b5516e27a701646f2ed92325bf8d
---
 .../js/features/pdf-preview/util/pdf-caching-flags.js      | 6 ++++++
 .../frontend/js/features/pdf-preview/util/pdf-caching.js   | 7 ++++---
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/services/web/frontend/js/features/pdf-preview/util/pdf-caching-flags.js b/services/web/frontend/js/features/pdf-preview/util/pdf-caching-flags.js
index 484b7e29b1..db7db3e439 100644
--- a/services/web/frontend/js/features/pdf-preview/util/pdf-caching-flags.js
+++ b/services/web/frontend/js/features/pdf-preview/util/pdf-caching-flags.js
@@ -1,6 +1,12 @@
 import getMeta from '../../../utils/meta'
 
+const hasTextEncoder = typeof TextEncoder !== 'undefined'
+if (!hasTextEncoder) {
+  console.warn('TextEncoder is not available. Disabling pdf-caching.')
+}
+
 function isFlagEnabled(flag) {
+  if (!hasTextEncoder) return false
   return getMeta('ol-splitTestVariants')?.[flag] === 'enabled'
 }
 
diff --git a/services/web/frontend/js/features/pdf-preview/util/pdf-caching.js b/services/web/frontend/js/features/pdf-preview/util/pdf-caching.js
index 569080f46c..e28a254b9c 100644
--- a/services/web/frontend/js/features/pdf-preview/util/pdf-caching.js
+++ b/services/web/frontend/js/features/pdf-preview/util/pdf-caching.js
@@ -5,12 +5,12 @@ const MAX_SUB_REQUEST_COUNT = 4
 const MAX_SUB_REQUEST_BYTES = 4 * PDF_JS_CHUNK_SIZE
 const INCREMENTAL_CACHE_SIZE = 1000
 
-const ENCODER = new TextEncoder()
 function backfillEdgeBounds(file) {
   if (!file.backfilledEdgeBoundsOnce) {
+    const encoder = new TextEncoder()
     for (const range of file.ranges) {
       if (range.objectId) {
-        range.objectId = ENCODER.encode(range.objectId)
+        range.objectId = encoder.encode(range.objectId)
         range.start -= range.objectId.byteLength
       }
     }
@@ -221,6 +221,7 @@ function getMultipartBoundary(response, chunk) {
 function resolveMultiPartResponses({ file, chunks, data, boundary, metrics }) {
   const responses = []
   let offsetStart = 0
+  const encoder = new TextEncoder()
   for (const chunk of chunks) {
     const header = `\r\n--${boundary}\r\nContent-Type: application/pdf\r\nContent-Range: bytes ${
       chunk.start
@@ -228,7 +229,7 @@ function resolveMultiPartResponses({ file, chunks, data, boundary, metrics }) {
     const headerSize = header.length
 
     // Verify header content. A proxy might have tampered with it.
-    const headerRaw = ENCODER.encode(header)
+    const headerRaw = encoder.encode(header)
     if (
       !data
         .subarray(offsetStart, offsetStart + headerSize)