From 70a63f7c626bf1982d7ee9d09e7a2ca943fcf046 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Viktor=20Dem=C4=8D=C3=A1k?=
 <71095952+vdemcak@users.noreply.github.com>
Date: Sat, 24 Jan 2026 21:21:43 +0100
Subject: [PATCH] [web] Fix Emscripten's Closure compiler error: undeclared
 canvas variable (#5507)

* Fix Emscripten Closure compiler error: undeclared canvas variable

* Fix hardcoded canvas IDs in web targets
---
 src/platforms/rcore_web.c            | 9 +++++----
 src/platforms/rcore_web_emscripten.c | 5 +++--
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/platforms/rcore_web.c b/src/platforms/rcore_web.c
index b0a145f67..986197b9d 100644
--- a/src/platforms/rcore_web.c
+++ b/src/platforms/rcore_web.c
@@ -316,15 +316,16 @@ void ToggleBorderlessWindowed(void)
         // 2. The style unset handles the possibility of a width="value%" like on the default shell.html file
         EM_ASM
         (
+            const canvasId = UTF8ToString($0);
             setTimeout(function()
             {
                 Module.requestFullscreen(false, true);
                 setTimeout(function()
                 {
-                    canvas.style.width="unset";
+                    document.querySelector(canvasId).style.width="unset";
                 }, 100);
             }, 100);
-        );
+        , platform.canvasId);
         FLAG_SET(CORE.Window.flags, FLAG_BORDERLESS_WINDOWED_MODE);
     }
 }
@@ -1238,9 +1239,9 @@ int InitPlatform(void)
     // Avoid creating a WebGL canvas, avoid calling glfwCreateWindow()
     emscripten_set_canvas_element_size(platform.canvasId, CORE.Window.screen.width, CORE.Window.screen.height);
     EM_ASM({
-        const canvas = document.getElementById("canvas");
+        const canvas = document.querySelector(UTF8ToString($0));
         Module.canvas = canvas;
-    });
+    }, platform.canvasId);
 
     // Load memory framebuffer with desired screen size
     // NOTE: Despite using a software framebuffer for blitting, GLFW still creates a WebGL canvas,
diff --git a/src/platforms/rcore_web_emscripten.c b/src/platforms/rcore_web_emscripten.c
index ad26077f4..ba2489a31 100644
--- a/src/platforms/rcore_web_emscripten.c
+++ b/src/platforms/rcore_web_emscripten.c
@@ -280,15 +280,16 @@ void ToggleBorderlessWindowed(void)
         // 2. The style unset handles the possibility of a width="value%" like on the default shell.html file
         EM_ASM
         (
+            const canvasId = UTF8ToString($0);
             setTimeout(function()
             {
                 Module.requestFullscreen(false, true);
                 setTimeout(function()
                 {
-                    canvas.style.width="unset";
+                    document.querySelector(canvasId).style.width="unset";
                 }, 100);
             }, 100);
-        );
+        , platform.canvasId);
         FLAG_SET(CORE.Window.flags, FLAG_BORDERLESS_WINDOWED_MODE);
     }
 }