3 files changed, 25 insertions, 0 deletions
diff --git a/platform/javascript/display_server_javascript.cpp b/platform/javascript/display_server_javascript.cpp
index 2f0a2faa83..2fd1f45939 100644
--- a/platform/javascript/display_server_javascript.cpp
+++ b/platform/javascript/display_server_javascript.cpp
@@ -829,6 +829,19 @@ DisplayServer *DisplayServerJavaScript::create_func(const String &p_rendering_dr
 }
 
 DisplayServerJavaScript::DisplayServerJavaScript(const String &p_rendering_driver, WindowMode p_mode, uint32_t p_flags, const Vector2i &p_resolution, Error &r_error) {
+	r_error = OK; // Always succeeds for now.
+
+	/* clang-format off */
+	swap_cancel_ok = EM_ASM_INT({
+		const win = (['Windows', 'Win64', 'Win32', 'WinCE']);
+		const plat = navigator.platform || "";
+		if (win.indexOf(plat) !== -1) {
+			return 1;
+		}
+		return 0;
+	}) == 1;
+	/* clang-format on */
+
 	RasterizerDummy::make_current(); // TODO GLES2 in Godot 4.0... or webgpu?
 #if 0
 	EmscriptenWebGLContextAttributes attributes;
@@ -1181,6 +1194,10 @@ int DisplayServerJavaScript::get_current_video_driver() const {
 	return 1;
 }
 
+bool DisplayServerJavaScript::get_swap_cancel_ok() {
+	return swap_cancel_ok;
+}
+
 void DisplayServerJavaScript::swap_buffers() {
 	//emscripten_webgl_commit_frame();
 }
diff --git a/platform/javascript/display_server_javascript.h b/platform/javascript/display_server_javascript.h
index b149665d67..6569ef1e42 100644
--- a/platform/javascript/display_server_javascript.h
+++ b/platform/javascript/display_server_javascript.h
@@ -56,6 +56,8 @@ class DisplayServerJavaScript : public DisplayServer {
 	int last_width = 0;
 	int last_height = 0;
 
+	bool swap_cancel_ok = false;
+
 	// utilities
 	static Point2 compute_position_in_canvas(int p_x, int p_y);
 	static void focus_canvas();
@@ -195,6 +197,7 @@ public:
 	virtual void set_icon(const Ref<Image> &p_icon);
 
 	// others
+	virtual bool get_swap_cancel_ok();
 	virtual void swap_buffers();
 
 	static void register_javascript_driver();
diff --git a/platform/javascript/javascript_main.cpp b/platform/javascript/javascript_main.cpp
index 99672745e7..a30d84a52c 100644
--- a/platform/javascript/javascript_main.cpp
+++ b/platform/javascript/javascript_main.cpp
@@ -34,6 +34,7 @@
 #include "platform/javascript/os_javascript.h"
 
 #include <emscripten/emscripten.h>
+#include <stdlib.h>
 
 static OS_JavaScript *os = nullptr;
 static uint64_t target_ticks = 0;
@@ -131,6 +132,10 @@ int main(int argc, char *argv[]) {
 	/* clang-format on */
 
 	os = new OS_JavaScript();
+
+	// We must override main when testing is enabled
+	TEST_MAIN_OVERRIDE
+
 	Main::setup(argv[0], argc - 1, &argv[1], false);
 	emscripten_set_main_loop(main_loop_callback, -1, false);
 	emscripten_pause_main_loop(); // Will need to wait for FS sync.