Disable deprecated find event target behavior (#9946)

* Default DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR=1

* Add note about DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR=1

* Add more details to the changelog

* Slightly improve formatting

* Update tests to use DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR=1 mode

* Fix OffscreenCanvas lookup when compiling without pthreads enabled

* Fix test_other

Author: juj

ChangeLog.md

@@ -17,6 +17,12 @@ See docs/process.md for how version tagging works.
 
 Current Trunk
 -------------
+- Default `DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR` to 1. See #9895.
+  With this change the old deprecated HTML5 API event target lookup behavior is
+  disabled. There is no "Module.canvas" object, no magic "null" default handling,
+  and DOM element 'target' parameters are taken to refer to CSS selectors, instead 
+  of referring to DOM IDs. For more information see:
+  https://groups.google.com/forum/#!msg/emscripten-discuss/xScZ_LRIByk/_gEy67utDgAJ
 
 v1.39.4: 12/03/2019
 -------------------

emcc.py

@@ -1118,7 +1118,6 @@ def check(input_file):
       shared.Settings.WASM_OBJECT_FILES = 0
 
     if shared.Settings.STRICT:
-      shared.Settings.DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR = 1
       shared.Settings.STRICT_JS = 1
       shared.Settings.AUTO_JS_LIBRARIES = 0
       shared.Settings.AUTO_ARCHIVE_INDEXES = 0
@@ -1531,9 +1530,6 @@ def is_supported_link_flag(f):
         # used and this special directive can be dropped.
         shared.Settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE += ['$warnOnce']
 
-      # Always use the new HTML5 API event target lookup rules
-      shared.Settings.DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR = 1
-
       # Require explicit -lfoo.js flags to link with JS libraries.
       shared.Settings.AUTO_JS_LIBRARIES = 0
 

src/library_html5.js

@@ -280,12 +280,6 @@ var LibraryJSEvents = {
     var domElement = __specialEventTargets[target] || (typeof document !== 'undefined' ? document.querySelector(__maybeCStringToJsString(target)) : undefined);
 #else
     var domElement = __specialEventTargets[target] || document.querySelector(__maybeCStringToJsString(target));
-#endif
-#if ASSERTIONS
-    // TODO: Remove this check in the future, or move it to some kind of debugging mode, because it may be perfectly fine behavior
-    // for one to query an event target to test if any DOM element with given CSS selector exists. However for a migration period
-    // from old lookup over to new, it is very useful to get diagnostics messages related to a lookup failing.
-    if (!domElement) err('No DOM element was found with CSS selector "' + __maybeCStringToJsString(target) + '"');
 #endif
     return domElement;
   },
@@ -295,15 +289,26 @@ var LibraryJSEvents = {
   _findCanvasEventTarget: function(target) {
     target = __maybeCStringToJsString(target);
 
-    // First look up if there exists an OffscreenCanvas with the given name.
-    var offscreenCanvas;
-    // TODO: Once Module['canvas'] is removed, clean up the following line:
-    if (target == '#canvas') offscreenCanvas = GL.offscreenCanvases['canvas'];
-    if (!offscreenCanvas) offscreenCanvas = GL.offscreenCanvases[target] || (target == 'canvas' && Object.keys(GL.offscreenCanvases)[0]); // First looks up by DOM ID ("#myCanvasElement"), second looks up by DOM element name (first found element of type <canvas>)
-    if (offscreenCanvas) return offscreenCanvas;
-
+    // When compiling with OffscreenCanvas support and looking up a canvas to target,
+    // we first look up if the target Canvas has been transferred to OffscreenCanvas use.
+    // These transfers are represented/tracked by GL.offscreenCanvases object, which contain
+    // the OffscreenCanvas element for each regular Canvas element that has been transferred.
+
+    // Note that each pthread/worker have their own set of GL.offscreenCanvases. That is,
+    // when an OffscreenCanvas is transferred from a pthread/main thread to another pthread,
+    // it will move in the GL.offscreenCanvases array between threads. Hence GL.offscreenCanvases
+    // represents the set of OffscreenCanvases owned by the current calling thread.
+
+    // First check out the list of OffscreenCanvases by CSS selector ID ('#myCanvasID')
+    return GL.offscreenCanvases[target.substr(1)] // Remove '#' prefix
+    // If not found, if one is querying by using DOM tag name selector 'canvas', grab the first
+    // OffscreenCanvas that we can find.
+     || (target == 'canvas' && Object.keys(GL.offscreenCanvases)[0])
+    // If that is not found either, query via the regular DOM selector.
 #if USE_PTHREADS
-    return (typeof document !== 'undefined') ? document.querySelector(target) : null;
+     || (typeof document !== 'undefined' && document.querySelector(target));
+#else
+     || document.querySelector(target);
 #endif
   },
 #else

src/settings.js

@@ -853,7 +853,6 @@ var LINKABLE = 0;
 // Set the environment variable EMCC_STRICT=1 or pass -s STRICT=1 to test that a
 // codebase builds nicely in forward compatible manner.
 // Changes enabled by this:
-//   * DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR is enabled.
 //   * The C define EMSCRIPTEN is not defined (__EMSCRIPTEN__ always is, and
 //     is the correct thing to use).
 //   * STRICT_JS is enabled.
@@ -1634,7 +1633,7 @@ var SUPPORT_LONGJMP = 1;
 // If set to 1, disables old deprecated HTML5 API event target lookup behavior. When enabled,
 // there is no "Module.canvas" object, no magic "null" default handling, and DOM element
 // 'target' parameters are taken to refer to CSS selectors, instead of referring to DOM IDs.
-var DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR = 0;
+var DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR = 1;
 
 // Specifies whether the generated .html file is run through html-minifier. The set of
 // optimization passes run by html-minifier depends on debug and optimization levels. In

tests/canvas_size_proxy.c

@@ -12,7 +12,7 @@ int main()
 {
     int result = 0;
     double w, h;
-    emscripten_get_element_css_size(NULL, &w, &h);
+    emscripten_get_element_css_size("#canvas", &w, &h);
     if (isnan(w) || isnan(h))
     {
         result = 1;

tests/emscripten_set_canvas_element_size.c

@@ -17,88 +17,38 @@ int main(int argc, char **argv)
   // For testing purposes, rename the canvas on the page to some arbitrary ID.
   EM_ASM(document.getElementById('canvas').id = 'myCanvasId');
 
-  // Accessing #canvas should resize Module['canvas']
-  EMSCRIPTEN_RESULT r = emscripten_set_canvas_element_size("#canvas", 100, 200);
+  // Test emscripten_set_canvas_element_size()
+  EMSCRIPTEN_RESULT r = emscripten_set_canvas_element_size("#myCanvasId", 100, 200);
   assert(r == EMSCRIPTEN_RESULT_SUCCESS);
 
   int w, h;
-  r = emscripten_get_canvas_element_size("#canvas", &w, &h);
+  r = emscripten_get_canvas_element_size("#myCanvasId", &w, &h);
   assert(r == EMSCRIPTEN_RESULT_SUCCESS);
   assert(w == 100);
   assert(h == 200);
   w = h = 0;
 
-  // Check that we see the change via 'NULL'
-  r = emscripten_get_canvas_element_size(NULL, &w, &h);
-  assert(r == EMSCRIPTEN_RESULT_SUCCESS);
-  assert(w == 100);
-  assert(h == 200);
-  w = h = 0;
-
-  // Check that we see the change via 'mycanvasId'
-  r = emscripten_get_canvas_element_size("myCanvasId", &w, &h);
-  assert(r == EMSCRIPTEN_RESULT_SUCCESS);
-  assert(w == 100);
-  assert(h == 200);
-
   // The following line will not work with OffscreenCanvas, that is covered in another test
-  int jsAgreesWithSize = EM_ASM_INT({return Module['canvas'].width == 100 && Module['canvas'].height == 200});
+  int jsAgreesWithSize = EM_ASM_INT({return document.querySelector('#myCanvasId').width == 100 && document.querySelector('#myCanvasId').height == 200});
   assert(jsAgreesWithSize);
 
-  // Accessing NULL should also resize Module['canvas']
-  r = emscripten_set_canvas_element_size(NULL, 101, 201);
-  assert(r == EMSCRIPTEN_RESULT_SUCCESS);
-
-  // Check that we see the change on the canvas (via the established #canvas)
-  r = emscripten_get_canvas_element_size("#canvas", &w, &h);
-  assert(r == EMSCRIPTEN_RESULT_SUCCESS);
-  assert(w == 101);
-  assert(h == 201);
-  w = h = 0;
-
-  // Check that we see the change via 'NULL'
-  r = emscripten_get_canvas_element_size(NULL, &w, &h);
-  assert(r == EMSCRIPTEN_RESULT_SUCCESS);
-  assert(w == 101);
-  assert(h == 201);
-  w = h = 0;
-
-  // Check that we see the change via 'mycanvasId'
-  r = emscripten_get_canvas_element_size("myCanvasId", &w, &h);
-  assert(r == EMSCRIPTEN_RESULT_SUCCESS);
-  assert(w == 101);
-  assert(h == 201);
-
   // Accessing by specific ID should resize canvas by that ID
-  r = emscripten_set_canvas_element_size("myCanvasId", 102, 202);
-  assert(r == EMSCRIPTEN_RESULT_SUCCESS);
-
-  // Check that we see the change on the canvas (via the established #canvas)
-  r = emscripten_get_canvas_element_size("#canvas", &w, &h);
+  r = emscripten_set_canvas_element_size("#myCanvasId", 102, 202);
   assert(r == EMSCRIPTEN_RESULT_SUCCESS);
-  assert(w == 102);
-  assert(h == 202);
 
-  // Check that we see the change on the canvas (via the established #canvas)
-  r = emscripten_get_canvas_element_size("#canvas", &w, &h);
+  // Check that we see the change on the canvas when querying with ID
+  r = emscripten_get_canvas_element_size("#myCanvasId", &w, &h);
   assert(r == EMSCRIPTEN_RESULT_SUCCESS);
   assert(w == 102);
   assert(h == 202);
-  w = h = 0;
 
-  // Check that we see the change via 'NULL'
-  r = emscripten_get_canvas_element_size(NULL, &w, &h);
+  // Check that we see the change on the canvas when querying with DOM element type
+  r = emscripten_get_canvas_element_size("canvas", &w, &h);
   assert(r == EMSCRIPTEN_RESULT_SUCCESS);
   assert(w == 102);
   assert(h == 202);
   w = h = 0;
 
-  // Check that we see the change via 'mycanvasId'
-  r = emscripten_get_canvas_element_size("myCanvasId", &w, &h);
-  assert(r == EMSCRIPTEN_RESULT_SUCCESS);
-  assert(w == 102);
-  assert(h == 202);
-
 #ifdef REPORT_RESULT
   REPORT_RESULT(1);
 #endif

tests/keydown_preventdefault_proxy.cpp

@@ -52,9 +52,9 @@ int main(int argc, char **argv)
 {
   printf("main argc:%d\n", argc);
 
-  emscripten_set_keydown_callback("#document", 0, 1, keydown_callback);
-  emscripten_set_keypress_callback("#document", 0, 1, keypress_callback);
-  emscripten_set_keyup_callback("#document", 0, 1, keyup_callback);
+  emscripten_set_keydown_callback(EMSCRIPTEN_EVENT_TARGET_DOCUMENT, 0, 1, keydown_callback);
+  emscripten_set_keypress_callback(EMSCRIPTEN_EVENT_TARGET_DOCUMENT, 0, 1, keypress_callback);
+  emscripten_set_keyup_callback(EMSCRIPTEN_EVENT_TARGET_DOCUMENT, 0, 1, keyup_callback);
 
   return 0;
 }

tests/other/metadce/hello_world_fastcomp_O3_MAIN_MODULE.sent

@@ -437,6 +437,7 @@ __inet_pton4_raw
 __inet_pton6
 __inet_pton6_raw
 __isLeapYear
+__maybeCStringToJsString
 __memory_base
 __polyfill_set_immediate
 __pthread_cleanup_pop

tests/test_browser.py

@@ -2563,13 +2563,13 @@ def test_doublestart_bug(self):
   def test_html5(self):
     for opts in [[], ['-O2', '-g1', '--closure', '1'], ['-s', 'USE_PTHREADS=1', '-s', 'PROXY_TO_PTHREAD=1']]:
       print(opts)
-      self.btest(path_from_root('tests', 'test_html5.c'), args=['-s', 'DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR=1'] + opts, expected='0')
+      self.btest(path_from_root('tests', 'test_html5.c'), args=[] + opts, expected='0')
 
   @requires_threads
   def test_html5_gamepad(self):
     for opts in [[], ['-O2', '-g1', '--closure', '1'], ['-s', 'USE_PTHREADS=1', '-s', 'PROXY_TO_PTHREAD=1']]:
       print(opts)
-      self.btest(path_from_root('tests', 'test_gamepad.c'), args=['-s', 'DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR=1'] + opts, expected='0')
+      self.btest(path_from_root('tests', 'test_gamepad.c'), args=[] + opts, expected='0')
 
   @requires_graphics_hardware
   def test_html5_webgl_create_context_no_antialias(self):
@@ -2587,14 +2587,15 @@ def test_html5_webgl_create_context(self):
 
   @requires_graphics_hardware
   # Verify bug https://github.com/emscripten-core/emscripten/issues/4556: creating a WebGL context to Module.canvas without an ID explicitly assigned to it.
+  # (this only makes sense in the old deprecated -s DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR=0 mode)
   def test_html5_webgl_create_context2(self):
-    self.btest(path_from_root('tests', 'webgl_create_context2.cpp'), args=['--shell-file', path_from_root('tests', 'webgl_create_context2_shell.html'), '-lGL'], expected='0')
+    self.btest(path_from_root('tests', 'webgl_create_context2.cpp'), args=['--shell-file', path_from_root('tests', 'webgl_create_context2_shell.html'), '-lGL', '-s', 'DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR=0'], expected='0')
 
   @requires_graphics_hardware
   def test_html5_webgl_destroy_context(self):
     for opts in [[], ['-O2', '-g1'], ['-s', 'FULL_ES2=1']]:
       print(opts)
-      self.btest(path_from_root('tests', 'webgl_destroy_context.cpp'), args=opts + ['-s', 'DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR=1', '--shell-file', path_from_root('tests/webgl_destroy_context_shell.html'), '-lGL'], expected='0')
+      self.btest(path_from_root('tests', 'webgl_destroy_context.cpp'), args=opts + ['--shell-file', path_from_root('tests/webgl_destroy_context_shell.html'), '-lGL'], expected='0')
 
   @no_chrome('see #7373')
   @requires_graphics_hardware
@@ -2665,7 +2666,7 @@ def test_sdl_touch(self):
   def test_html5_mouse(self):
     for opts in [[], ['-O2', '-g1', '--closure', '1']]:
       print(opts)
-      self.btest(path_from_root('tests', 'test_html5_mouse.c'), args=opts + ['-s', 'DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR=1', '-DAUTOMATE_SUCCESS=1'], expected='0')
+      self.btest(path_from_root('tests', 'test_html5_mouse.c'), args=opts + ['-DAUTOMATE_SUCCESS=1'], expected='0')
 
   def test_sdl_mousewheel(self):
     for opts in [[], ['-O2', '-g1', '--closure', '1']]:
@@ -4233,7 +4234,7 @@ def test_small_js_flags(self):
   @requires_offscreen_canvas
   def test_webgl_offscreen_canvas_in_pthread(self):
     for args in [[], ['-DTEST_CHAINED_WEBGL_CONTEXT_PASSING']]:
-      self.btest('gl_in_pthread.cpp', expected='1', args=args + ['-s', 'USE_PTHREADS=1', '-s', 'PTHREAD_POOL_SIZE=2', '-s', 'OFFSCREENCANVAS_SUPPORT=1', '-lGL', '-s', 'DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR=1'])
+      self.btest('gl_in_pthread.cpp', expected='1', args=args + ['-s', 'USE_PTHREADS=1', '-s', 'PTHREAD_POOL_SIZE=2', '-s', 'OFFSCREENCANVAS_SUPPORT=1', '-lGL'])
 
   # Tests that it is possible to render WebGL content on a <canvas> on the main thread, after it has once been used to render WebGL content in a pthread first
   # -DTEST_MAIN_THREAD_EXPLICIT_COMMIT: Test the same (WebGL on main thread after pthread), but by using explicit .commit() to swap on the main thread instead of implicit "swap when rAF ends" logic
@@ -4242,12 +4243,12 @@ def test_webgl_offscreen_canvas_in_pthread(self):
   def test_webgl_offscreen_canvas_in_mainthread_after_pthread(self):
     self.skipTest('This test is disabled because current OffscreenCanvas does not allow transfering it after a rendering context has been created for it.')
     for args in [[], ['-DTEST_MAIN_THREAD_EXPLICIT_COMMIT']]:
-      self.btest('gl_in_mainthread_after_pthread.cpp', expected='0', args=args + ['-s', 'USE_PTHREADS=1', '-s', 'PTHREAD_POOL_SIZE=2', '-s', 'OFFSCREENCANVAS_SUPPORT=1', '-lGL', '-s', 'DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR=1'])
+      self.btest('gl_in_mainthread_after_pthread.cpp', expected='0', args=args + ['-s', 'USE_PTHREADS=1', '-s', 'PTHREAD_POOL_SIZE=2', '-s', 'OFFSCREENCANVAS_SUPPORT=1', '-lGL'])
 
   @requires_threads
   @requires_offscreen_canvas
   def test_webgl_offscreen_canvas_only_in_pthread(self):
-    self.btest('gl_only_in_pthread.cpp', expected='0', args=['-s', 'USE_PTHREADS=1', '-s', 'PTHREAD_POOL_SIZE=1', '-s', 'OFFSCREENCANVAS_SUPPORT=1', '-lGL', '-s', 'DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR=1', '-s', 'OFFSCREEN_FRAMEBUFFER=1'])
+    self.btest('gl_only_in_pthread.cpp', expected='0', args=['-s', 'USE_PTHREADS=1', '-s', 'PTHREAD_POOL_SIZE=1', '-s', 'OFFSCREENCANVAS_SUPPORT=1', '-lGL', '-s', 'OFFSCREEN_FRAMEBUFFER=1'])
 
   # Tests that rendering from client side memory without default-enabling extensions works.
   @requires_graphics_hardware
@@ -4300,7 +4301,7 @@ def test_webgl_array_of_structs_uniform(self):
   @requires_offscreen_canvas
   def test_webgl_offscreen_canvas_in_proxied_pthread(self):
     for asyncify in [0, 1]:
-      cmd = ['-s', 'USE_PTHREADS=1', '-s', 'OFFSCREENCANVAS_SUPPORT=1', '-lGL', '-s', 'GL_DEBUG=1', '-s', 'PROXY_TO_PTHREAD=1', '-s', 'DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR=1']
+      cmd = ['-s', 'USE_PTHREADS=1', '-s', 'OFFSCREENCANVAS_SUPPORT=1', '-lGL', '-s', 'GL_DEBUG=1', '-s', 'PROXY_TO_PTHREAD=1']
       if asyncify:
         if not self.is_wasm_backend():
           continue
@@ -4316,7 +4317,7 @@ def test_webgl_resize_offscreencanvas_from_main_thread(self):
     for args1 in [[], ['-s', 'PROXY_TO_PTHREAD=1']]:
       for args2 in [[], ['-DTEST_SYNC_BLOCKING_LOOP=1']]:
         for args3 in [[], ['-s', 'OFFSCREENCANVAS_SUPPORT=1', '-s', 'OFFSCREEN_FRAMEBUFFER=1']]:
-          cmd = args1 + args2 + args3 + ['-s', 'USE_PTHREADS=1', '-lGL', '-s', 'GL_DEBUG=1', '-s', 'DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR=1']
+          cmd = args1 + args2 + args3 + ['-s', 'USE_PTHREADS=1', '-lGL', '-s', 'GL_DEBUG=1']
           print(str(cmd))
           self.btest('resize_offscreencanvas_from_main_thread.cpp', expected='1', args=cmd)
 

tests/test_other.py

@@ -8231,7 +8231,7 @@ def test_metadce_hello(self, *args):
                       4, [],        [],           8,   0,    0,  0), # noqa; totally empty!
     # we don't metadce with linkable code! other modules may want stuff
     # don't compare the # of functions in a main module, which changes a lot
-    'main_module_1': (['-O3', '-s', 'MAIN_MODULE=1'], 1605, [], [], 226403, None, 108, None), # noqa
+    'main_module_1': (['-O3', '-s', 'MAIN_MODULE=1'], 1606, [], [], 226403, None, 108, None), # noqa
     'main_module_2': (['-O3', '-s', 'MAIN_MODULE=2'],   13, [], [],  10017,   13,   9,   20), # noqa
   })
   @no_wasm_backend()

tests/webgl2_objects.cpp

@@ -36,7 +36,7 @@ int main()
   attrs.majorVersion = 2;
   attrs.minorVersion = 0;
 
-  EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context = emscripten_webgl_create_context( 0, &attrs );
+  EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context = emscripten_webgl_create_context( "#canvas", &attrs );
   if (!context)
   {
     printf("Skipped: WebGL 2 is not supported.\n");

tests/webgl2_pbo.cpp

@@ -37,7 +37,7 @@ int main()
   attrs.majorVersion = 2;
   attrs.minorVersion = 0;
 
-  EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context = emscripten_webgl_create_context( 0, &attrs );
+  EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context = emscripten_webgl_create_context( "#canvas", &attrs );
   if (!context)
   {
     printf("Skipped: WebGL 2 is not supported.\n");

tests/webgl2_ubos.cpp

@@ -35,7 +35,7 @@ int main()
   attrs.majorVersion = 2;
   attrs.minorVersion = 0;
 
-  EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context = emscripten_webgl_create_context( 0, &attrs );
+  EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context = emscripten_webgl_create_context( "#canvas", &attrs );
   if (!context)
   {
     printf("Skipped: WebGL 2 is not supported.\n");

tests/webgl_create_context.cpp

@@ -107,7 +107,7 @@ int main()
     );
 
     assert(emscripten_webgl_get_current_context() == 0);
-    EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context = emscripten_webgl_create_context("customCanvas", &attrs);
+    EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context = emscripten_webgl_create_context("#customCanvas", &attrs);
     assert(context > 0); // Must have received a valid context.
     EMSCRIPTEN_RESULT res = emscripten_webgl_make_context_current(context);
     assert(res == EMSCRIPTEN_RESULT_SUCCESS);

tests/webgl_create_context2.cpp

@@ -14,6 +14,8 @@ int main()
 {
   EmscriptenWebGLContextAttributes attrs;
   emscripten_webgl_init_context_attributes(&attrs);
+  // Test that creating a context with #canvas target when -s DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR=0
+  // will create a canvas against Module.canvas
   EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context = emscripten_webgl_create_context("#canvas", &attrs);
   assert(context > 0); // Must have received a valid context.
   EMSCRIPTEN_RESULT res = emscripten_webgl_make_context_current(context);

tests/webgl_shader_source_length.cpp

@@ -33,7 +33,7 @@ int main()
   EmscriptenWebGLContextAttributes attrs;
   emscripten_webgl_init_context_attributes(&attrs);
 
-  EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context = emscripten_webgl_create_context( 0, &attrs );
+  EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context = emscripten_webgl_create_context( "#canvas", &attrs );
   if (!context)
   {
     printf("Skipped: WebGL is not supported.\n");

tests/webgl_with_closure.cpp

@@ -76,11 +76,11 @@ int main()
     attrs.majorVersion = 2;
     attrs.minorVersion = 0;
 
-    EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context = emscripten_webgl_create_context( 0, &attrs );
+    EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context = emscripten_webgl_create_context( "#canvas", &attrs );
     if (!context)
     {
         attrs.majorVersion = 1;
-        context = emscripten_webgl_create_context( 0, &attrs );
+        context = emscripten_webgl_create_context( "#canvas", &attrs );
         if (context) printf("Skipping test: WebGL 2.0 is not available.\n");
         else printf("Test failed: WebGL is not available!\n");
 #ifdef REPORT_RESULT