From 82a0bcecfa6a52ad2716e62cfa397c8850f231d2 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Wed, 12 Apr 2023 13:57:10 +0200
Subject: [PATCH] Skip transfers, in `LoopbackPort.postMessage`, for PDF.js
 `legacy`-builds (issue 16255)

Apparently the `structuredClone` polyfill doesn't handle transfers correctly, and `DOMException`s may thus be thrown. This is particularly problematical in Node.js environments, where that exception (obviously) isn't available.

To work-around these issues we'll simply ignore any transfers in `legacy`-builds, since those *may* use the `structuredClone` polyfill. This will obviously lead to slightly higher memory usage in those builds, however this really only affects Node.js environments. (Browsers are only affected if workers are disabled, however that's never been an officially recommended/supported configuration.)
---
 src/display/api.js | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/display/api.js b/src/display/api.js
index 93a3c890a..de5ad9e6c 100644
--- a/src/display/api.js
+++ b/src/display/api.js
@@ -1943,7 +1943,14 @@ class LoopbackPort {
 
   postMessage(obj, transfer) {
     const event = {
-      data: structuredClone(obj, transfer ? { transfer } : null),
+      data: structuredClone(
+        obj,
+        (typeof PDFJSDev === "undefined" ||
+          PDFJSDev.test("SKIP_BABEL || TESTING")) &&
+          transfer
+          ? { transfer }
+          : null
+      ),
     };
 
     this.#deferred.then(() => {