5 files changed, 28 insertions, 9 deletions
diff --git a/platform/javascript/detect.py b/platform/javascript/detect.py
index 8472c3ccab..8c7a904bca 100644
--- a/platform/javascript/detect.py
+++ b/platform/javascript/detect.py
@@ -49,8 +49,14 @@ def configure(env):
     ## Build type
 
     if (env["target"] == "release"):
-        env.Append(CCFLAGS=['-O3'])
-        env.Append(LINKFLAGS=['-O3'])
+        # Use -Os to prioritize optimizing for reduced file size. This is
+        # particularly valuable for the web platform because it directly
+        # decreases download time.
+        # -Os reduces file size by around 5 MiB over -O3. -Oz only saves about
+        # 100 KiB over -Os, which does not justify the negative impact on
+        # run-time performance.
+        env.Append(CCFLAGS=['-Os'])
+        env.Append(LINKFLAGS=['-Os'])
 
     elif (env["target"] == "release_debug"):
         env.Append(CCFLAGS=['-O2', '-DDEBUG_ENABLED'])
diff --git a/platform/javascript/engine.js b/platform/javascript/engine.js
index dc4bdc7efb..bca1851f40 100644
--- a/platform/javascript/engine.js
+++ b/platform/javascript/engine.js
@@ -138,13 +138,17 @@
 			}
 
 			var actualCanvas = this.rtenv.canvas;
-			var context = false;
+			var testContext = false;
+			var testCanvas;
 			try {
-				context = actualCanvas.getContext('webgl2') || actualCanvas.getContext('experimental-webgl2');
+				testCanvas = document.createElement('canvas');
+				testContext = testCanvas.getContext('webgl2') || testCanvas.getContext('experimental-webgl2');
 			} catch (e) {}
-			if (!context) {
+			if (!testContext) {
 				throw new Error("WebGL 2 not available");
 			}
+			testCanvas = null;
+			testContext = null;
 
 			// canvas can grab focus on click
 			if (actualCanvas.tabIndex < 0) {
diff --git a/platform/javascript/javascript_main.cpp b/platform/javascript/javascript_main.cpp
index b738f37d1b..e85fe0800f 100644
--- a/platform/javascript/javascript_main.cpp
+++ b/platform/javascript/javascript_main.cpp
@@ -65,7 +65,7 @@ int main(int argc, char *argv[]) {
 		FS.mkdir('/userfs');
 		FS.mount(IDBFS, {}, '/userfs');
 		FS.syncfs(true, function(err) {
-			Module['ccall']('main_after_fs_sync', null, ['string'], [err ? err.message : ""])
+			ccall('main_after_fs_sync', null, ['string'], [err ? err.message : ""])
 		});
 	);
 	/* clang-format on */
diff --git a/platform/javascript/os_javascript.cpp b/platform/javascript/os_javascript.cpp
index c598557738..b10ef821dd 100644
--- a/platform/javascript/os_javascript.cpp
+++ b/platform/javascript/os_javascript.cpp
@@ -566,7 +566,7 @@ void OS_JavaScript::set_css_cursor(const char *p_cursor) {
 
 	/* clang-format off */
 	EM_ASM_({
-		Module.canvas.style.cursor = Module.UTF8ToString($0);
+		Module.canvas.style.cursor = UTF8ToString($0);
 	}, p_cursor);
 	/* clang-format on */
 }
@@ -576,7 +576,7 @@ const char *OS_JavaScript::get_css_cursor() const {
 	char cursor[16];
 	/* clang-format off */
 	EM_ASM_INT({
-		Module.stringToUTF8(Module.canvas.style.cursor ? Module.canvas.style.cursor : 'auto', $0, 16);
+		stringToUTF8(Module.canvas.style.cursor ? Module.canvas.style.cursor : 'auto', $0, 16);
 	}, cursor);
 	/* clang-format on */
 	return cursor;
@@ -782,6 +782,9 @@ void OS_JavaScript::set_cursor_shape(CursorShape p_shape) {
 		set_css_cursor(godot2dom_cursor(cursor_shape));
 }
 
+void OS_JavaScript::set_custom_mouse_cursor(const RES &p_cursor, CursorShape p_shape, const Vector2 &p_hotspot) {
+}
+
 void OS_JavaScript::main_loop_begin() {
 
 	if (main_loop)
@@ -789,7 +792,7 @@ void OS_JavaScript::main_loop_begin() {
 
 	/* clang-format off */
 	EM_ASM_ARGS({
-		const send_notification = Module.cwrap('send_notification', null, ['number']);
+		const send_notification = cwrap('send_notification', null, ['number']);
 		const notifs = arguments;
 		(['mouseover', 'mouseleave', 'focus', 'blur']).forEach(function(event, i) {
 			Module.canvas.addEventListener(event, send_notification.bind(null, notifs[i]));
@@ -986,6 +989,7 @@ bool OS_JavaScript::is_userfs_persistent() const {
 }
 
 OS_JavaScript::OS_JavaScript(const char *p_execpath, GetUserDataDirFunc p_get_user_data_dir_func) {
+
 	set_cmdline(p_execpath, get_cmdline_args());
 	main_loop = NULL;
 	gl_extensions = NULL;
@@ -998,6 +1002,10 @@ OS_JavaScript::OS_JavaScript(const char *p_execpath, GetUserDataDirFunc p_get_us
 
 	idbfs_available = false;
 	time_to_save_sync = -1;
+
+	Vector<Logger *> loggers;
+	loggers.push_back(memnew(StdLogger));
+	_set_logger(memnew(CompositeLogger(loggers)));
 }
 
 OS_JavaScript::~OS_JavaScript() {
diff --git a/platform/javascript/os_javascript.h b/platform/javascript/os_javascript.h
index 2af90ef16b..ce4763ab64 100644
--- a/platform/javascript/os_javascript.h
+++ b/platform/javascript/os_javascript.h
@@ -128,6 +128,7 @@ public:
 	virtual bool is_userfs_persistent() const;
 
 	virtual void set_cursor_shape(CursorShape p_shape);
+	virtual void set_custom_mouse_cursor(const RES &p_cursor, CursorShape p_shape, const Vector2 &p_hotspot);
 
 	void main_loop_begin();
 	bool main_loop_iterate();