16 files changed, 332 insertions, 384 deletions

diff --git a/platform/javascript/SCsub b/platform/javascript/SCsub
index 66a8a8d93c..98988d97fd 100644
--- a/platform/javascript/SCsub
+++ b/platform/javascript/SCsub
@@ -3,38 +3,35 @@
 Import('env')
 
 javascript_files = [
-    "os_javascript.cpp",
-    "audio_driver_javascript.cpp",
-    "javascript_main.cpp",
-    "power_javascript.cpp",
-    "http_client_javascript.cpp",
-    "javascript_eval.cpp",
+    'audio_driver_javascript.cpp',
+    'http_client_javascript.cpp',
+    'javascript_eval.cpp',
+    'javascript_main.cpp',
+    'os_javascript.cpp',
 ]
 
-env_javascript = env.Clone()
-if env['target'] == "profile":
-    env_javascript.Append(CPPFLAGS=['-DPROFILER_ENABLED'])
-
-javascript_objects = []
-for x in javascript_files:
-    javascript_objects.append(env_javascript.Object(x))
-
-env.Append(LINKFLAGS=["-s", "EXPORTED_FUNCTIONS=\"['_main','_main_after_fs_sync','_send_notification']\""])
-
-target_dir = env.Dir("#bin")
-build = env.add_program(['#bin/godot', target_dir.File('godot' + env['PROGSUFFIX'] + '.wasm')], javascript_objects, PROGSUFFIX=env['PROGSUFFIX'] + '.js');
+build = env.add_program(['#bin/godot${PROGSUFFIX}.js', '#bin/godot${PROGSUFFIX}.wasm'], javascript_files);
 js, wasm = build
 
-js_libraries = []
-js_libraries.append(env.File('http_request.js'))
+js_libraries = [
+    'http_request.js',
+]
 for lib in js_libraries:
-    env.Append(LINKFLAGS=['--js-library', lib.path])
+    env.Append(LINKFLAGS=['--js-library', env.File(lib).path])
 env.Depends(build, js_libraries)
 
 wrapper_start = env.File('pre.js')
 wrapper_end = env.File('engine.js')
-js_final = env.Textfile('#bin/godot', [wrapper_start, js, wrapper_end], TEXTFILESUFFIX=env['PROGSUFFIX'] + '.wrapped.js')
-
-zip_dir = target_dir.Dir('.javascript_zip')
-zip_files = env.InstallAs([zip_dir.File('godot.js'), zip_dir.File('godot.wasm'), zip_dir.File('godot.html')], [js_final, wasm, '#misc/dist/html/default.html'])
-Zip('#bin/godot', zip_files, ZIPSUFFIX=env['PROGSUFFIX'] + env['ZIPSUFFIX'], ZIPROOT=zip_dir, ZIPCOMSTR="Archving $SOURCES as $TARGET")
+js_wrapped = env.Textfile('#bin/godot', [wrapper_start, js, wrapper_end], TEXTFILESUFFIX='${PROGSUFFIX}.wrapped.js')
+
+zip_dir = env.Dir('#bin/.javascript_zip')
+zip_files = env.InstallAs([
+    zip_dir.File('godot.js'),
+    zip_dir.File('godot.wasm'),
+    zip_dir.File('godot.html')
+], [
+    js_wrapped,
+    wasm,
+    '#misc/dist/html/default.html'
+])
+env.Zip('#bin/godot', zip_files, ZIPROOT=zip_dir, ZIPSUFFIX='${PROGSUFFIX}${ZIPSUFFIX}', ZIPCOMSTR='Archving $SOURCES as $TARGET')
diff --git a/platform/javascript/audio_driver_javascript.cpp b/platform/javascript/audio_driver_javascript.cpp
index 5bf345e6cd..7a6613bb32 100644
--- a/platform/javascript/audio_driver_javascript.cpp
+++ b/platform/javascript/audio_driver_javascript.cpp
@@ -32,113 +32,134 @@
 
 #include <emscripten.h>
 
-AudioDriverJavaScript *AudioDriverJavaScript::singleton_js = NULL;
+AudioDriverJavaScript *AudioDriverJavaScript::singleton = NULL;
 
 const char *AudioDriverJavaScript::get_name() const {
 
 	return "JavaScript";
 }
 
-extern "C" EMSCRIPTEN_KEEPALIVE void js_audio_driver_mix_function(int p_frames) {
+extern "C" EMSCRIPTEN_KEEPALIVE void audio_driver_js_mix() {
 
-	//print_line("MIXI! "+itos(p_frames));
-	AudioDriverJavaScript::singleton_js->mix_to_js(p_frames);
+	AudioDriverJavaScript::singleton->mix_to_js();
 }
 
-void AudioDriverJavaScript::mix_to_js(int p_frames) {
+void AudioDriverJavaScript::mix_to_js() {
 
-	int todo = p_frames;
-	int offset = 0;
+	int channel_count = get_total_channels_by_speaker_mode(get_speaker_mode());
+	int sample_count = memarr_len(internal_buffer) / channel_count;
+	int32_t *stream_buffer = reinterpret_cast<int32_t *>(internal_buffer);
+	audio_server_process(sample_count, stream_buffer);
+	for (int i = 0; i < sample_count * channel_count; i++) {
+		internal_buffer[i] = float(stream_buffer[i] >> 16) / 32768.0;
+	}
+}
 
-	while (todo) {
+Error AudioDriverJavaScript::init() {
 
-		int tomix = MIN(todo, INTERNAL_BUFFER_SIZE);
+	/* clang-format off */
+	EM_ASM({
+		_audioDriver_audioContext = new (window.AudioContext || window.webkitAudioContext);
+		_audioDriver_scriptNode = null;
+	});
+	/* clang-format on */
 
-		audio_server_process(p_frames, stream_buffer);
-		for (int i = 0; i < tomix * internal_buffer_channels; i++) {
-			internal_buffer[i] = float(stream_buffer[i] >> 16) / 32768.0;
+	int channel_count = get_total_channels_by_speaker_mode(get_speaker_mode());
+	/* clang-format off */
+	int buffer_length = EM_ASM_INT({
+		var CHANNEL_COUNT = $0;
+
+		var channelCount = _audioDriver_audioContext.destination.channelCount;
+		try {
+			// Try letting the browser recommend a buffer length.
+			_audioDriver_scriptNode = _audioDriver_audioContext.createScriptProcessor(0, 0, channelCount);
+		} catch (e) {
+			// ...otherwise, default to 4096.
+			_audioDriver_scriptNode = _audioDriver_audioContext.createScriptProcessor(4096, 0, channelCount);
 		}
+		_audioDriver_scriptNode.connect(_audioDriver_audioContext.destination);
 
-		/* clang-format off */
-		EM_ASM_ARGS({
-			var data = HEAPF32.subarray($0 / 4, $0 / 4 + $2 * 2);
-
-			for (var channel = 0; channel < _as_output_buffer.numberOfChannels; channel++) {
-				var outputData = _as_output_buffer.getChannelData(channel);
-				// Loop through samples
-				for (var sample = 0; sample < $2; sample++) {
-					// make output equal to the same as the input
-					outputData[sample + $1] = data[sample * 2 + channel];
-				}
-			}
-		}, internal_buffer, offset, tomix);
-		/* clang-format on */
-
-		todo -= tomix;
-		offset += tomix;
+		return _audioDriver_scriptNode.bufferSize;
+	}, channel_count);
+	/* clang-format on */
+	if (!buffer_length) {
+		return FAILED;
 	}
-}
-
-Error AudioDriverJavaScript::init() {
 
-	return OK;
+	if (!internal_buffer || memarr_len(internal_buffer) != buffer_length * channel_count) {
+		if (internal_buffer)
+			memdelete_arr(internal_buffer);
+		internal_buffer = memnew_arr(float, buffer_length *channel_count);
+	}
+	return internal_buffer ? OK : ERR_OUT_OF_MEMORY;
 }
 
 void AudioDriverJavaScript::start() {
 
-	internal_buffer = memnew_arr(float, INTERNAL_BUFFER_SIZE *internal_buffer_channels);
-	stream_buffer = memnew_arr(int32_t, INTERNAL_BUFFER_SIZE * 4); //max 4 channels
-
 	/* clang-format off */
-	mix_rate = EM_ASM_INT({
-		_as_audioctx = new (window.AudioContext || window.webkitAudioContext);
-		_as_script_node = _as_audioctx.createScriptProcessor($0, 0, $1);
-		_as_script_node.connect(_as_audioctx.destination);
-		console.log(_as_script_node.bufferSize);
-		var jsAudioDriverMixFunction = cwrap('js_audio_driver_mix_function', null, ['number']);
-
-		_as_script_node.onaudioprocess = function(audioProcessingEvent) {
-			// The output buffer contains the samples that will be modified and played
-			_as_output_buffer = audioProcessingEvent.outputBuffer;
-			jsAudioDriverMixFunction([_as_output_buffer.getChannelData(0).length]);
+	EM_ASM({
+		var INTERNAL_BUFFER_PTR = $0;
+
+		var audioDriverMixFunction = cwrap('audio_driver_js_mix');
+		_audioDriver_scriptNode.onaudioprocess = function(audioProcessingEvent) {
+			audioDriverMixFunction();
+			// The output buffer contains the samples that will be modified and played.
+			var output = audioProcessingEvent.outputBuffer;
+			var input = HEAPF32.subarray(
+					INTERNAL_BUFFER_PTR / HEAPF32.BYTES_PER_ELEMENT,
+					INTERNAL_BUFFER_PTR / HEAPF32.BYTES_PER_ELEMENT + output.length * output.numberOfChannels);
+
+			for (var channel = 0; channel < output.numberOfChannels; channel++) {
+				var outputData = output.getChannelData(channel);
+				// Loop through samples.
+				for (var sample = 0; sample < outputData.length; sample++) {
+					// Set output equal to input.
+					outputData[sample] = input[sample * output.numberOfChannels + channel];
+				}
+			}
 		};
-		return _as_audioctx.sampleRate;
-	}, INTERNAL_BUFFER_SIZE, internal_buffer_channels);
+	}, internal_buffer);
 	/* clang-format on */
 }
 
 int AudioDriverJavaScript::get_mix_rate() const {
 
-	return mix_rate;
+	/* clang-format off */
+	return EM_ASM_INT_V({
+		return _audioDriver_audioContext.sampleRate;
+	});
+	/* clang-format on */
 }
 
 AudioDriver::SpeakerMode AudioDriverJavaScript::get_speaker_mode() const {
 
-	return SPEAKER_MODE_STEREO;
+	/* clang-format off */
+	return get_speaker_mode_by_total_channels(EM_ASM_INT_V({
+		return _audioDriver_audioContext.destination.channelCount;
+	}));
+	/* clang-format on */
 }
 
+// No locking, as threads are not supported.
 void AudioDriverJavaScript::lock() {
-
-	/*no locking, as threads are not supported
-	if (active && mutex)
-		mutex->lock();
-	*/
 }
 
 void AudioDriverJavaScript::unlock() {
-
-	/*no locking, as threads are not supported
-	if (active && mutex)
-		mutex->unlock();
-	*/
 }
 
 void AudioDriverJavaScript::finish() {
+
+	/* clang-format off */
+	EM_ASM({
+		_audioDriver_audioContext = null;
+		_audioDriver_scriptNode = null;
+	});
+	/* clang-format on */
+	memdelete_arr(internal_buffer);
+	internal_buffer = NULL;
 }
 
 AudioDriverJavaScript::AudioDriverJavaScript() {
 
-	internal_buffer_channels = 2;
-	mix_rate = DEFAULT_MIX_RATE;
-	singleton_js = this;
+	singleton = this;
 }
diff --git a/platform/javascript/audio_driver_javascript.h b/platform/javascript/audio_driver_javascript.h
index d78ab8eea4..a65a8ec29f 100644
--- a/platform/javascript/audio_driver_javascript.h
+++ b/platform/javascript/audio_driver_javascript.h
@@ -35,18 +35,11 @@
 
 class AudioDriverJavaScript : public AudioDriver {
 
-	enum {
-		INTERNAL_BUFFER_SIZE = 4096,
-	};
-
-	int mix_rate;
 	float *internal_buffer;
-	int internal_buffer_channels;
-	int32_t *stream_buffer;
 
 public:
-	void mix_to_js(int p_frames);
-	static AudioDriverJavaScript *singleton_js;
+	void mix_to_js();
+	static AudioDriverJavaScript *singleton;
 
 	virtual const char *get_name() const;
 
diff --git a/platform/javascript/detect.py b/platform/javascript/detect.py
index 74d6536343..fc909f6619 100644
--- a/platform/javascript/detect.py
+++ b/platform/javascript/detect.py
@@ -1,5 +1,4 @@
 import os
-import string
 import sys
 
 
@@ -8,52 +7,38 @@ def is_active():
 
 
 def get_name():
-    return "JavaScript"
+    return 'JavaScript'
 
 
 def can_build():
-
-    return ("EMSCRIPTEN_ROOT" in os.environ or "EMSCRIPTEN" in os.environ)
+    return 'EM_CONFIG' in os.environ or os.path.exists(os.path.expanduser('~/.emscripten'))
 
 
 def get_opts():
     from SCons.Variables import BoolVariable
     return [
+        # eval() can be a security concern, so it can be disabled.
         BoolVariable('javascript_eval', 'Enable JavaScript eval interface', True),
     ]
 
 
 def get_flags():
-
     return [
         ('tools', False),
         ('module_theora_enabled', False),
-        # Disabling the OpenSSL module noticeably reduces file size.
+        # Disabling the mbedtls module reduces file size.
         # The module has little use due to the limited networking functionality
         # in this platform. For the available networking methods, the browser
         # manages TLS.
-        ('module_openssl_enabled', False),
+        ('module_mbedtls_enabled', False),
     ]
 
 
-def create(env):
-
-    # remove Windows' .exe suffix
-    return env.Clone(tools=['textfile', 'zip'], PROGSUFFIX='')
-
-
-def escape_sources_backslashes(target, source, env, for_signature):
-    return [path.replace('\\','\\\\') for path in env.GetBuildPath(source)]
-
-def escape_target_backslashes(target, source, env, for_signature):
-    return env.GetBuildPath(target[0]).replace('\\','\\\\')
-
-
 def configure(env):
 
     ## Build type
 
-    if (env["target"] == "release"):
+    if env['target'] != 'debug':
         # Use -Os to prioritize optimizing for reduced file size. This is
         # particularly valuable for the web platform because it directly
         # decreases download time.
@@ -62,65 +47,96 @@ def configure(env):
         # run-time performance.
         env.Append(CCFLAGS=['-Os'])
         env.Append(LINKFLAGS=['-Os'])
-
-    elif (env["target"] == "release_debug"):
-        env.Append(CCFLAGS=['-O2', '-DDEBUG_ENABLED'])
-        env.Append(LINKFLAGS=['-O2', '-s', 'ASSERTIONS=1'])
-        # retain function names at the cost of file size, for backtraces and profiling
-        env.Append(LINKFLAGS=['--profiling-funcs'])
-
-    elif (env["target"] == "debug"):
-        env.Append(CCFLAGS=['-O1', '-D_DEBUG', '-g', '-DDEBUG_ENABLED'])
+        if env['target'] == 'release_debug':
+            env.Append(CPPDEFINES=['DEBUG_ENABLED'])
+            # Retain function names for backtraces at the cost of file size.
+            env.Append(LINKFLAGS=['--profiling-funcs'])
+    else:
+        env.Append(CPPDEFINES=['DEBUG_ENABLED'])
+        env.Append(CCFLAGS=['-O1', '-g'])
         env.Append(LINKFLAGS=['-O1', '-g'])
+        env.Append(LINKFLAGS=['-s', 'ASSERTIONS=1'])
 
     ## Compiler configuration
 
     env['ENV'] = os.environ
-    if ("EMSCRIPTEN_ROOT" in os.environ):
-        env.PrependENVPath('PATH', os.environ['EMSCRIPTEN_ROOT'])
-    elif ("EMSCRIPTEN" in os.environ):
-        env.PrependENVPath('PATH', os.environ['EMSCRIPTEN'])
-    env['CC']      = 'emcc'
-    env['CXX']     = 'em++'
-    env['LINK']    = 'emcc'
-    env['RANLIB']  = 'emranlib'
-    # Emscripten's ar has issues with duplicate file names, so use cc
-    env['AR']      = 'emcc'
-    env['ARFLAGS'] = '-o'
-
-    if (os.name == 'nt'):
-        # use TempFileMunge on Windows since some commands get too long for
-        # cmd.exe even with spawn_fix
-        # need to escape backslashes for this
-        env['ESCAPED_SOURCES'] = escape_sources_backslashes
-        env['ESCAPED_TARGET'] = escape_target_backslashes
-        env['ARCOM'] = '${TEMPFILE("%s")}' % env['ARCOM'].replace('$SOURCES', '$ESCAPED_SOURCES').replace('$TARGET', '$ESCAPED_TARGET')
 
+    em_config_file = os.getenv('EM_CONFIG') or os.path.expanduser('~/.emscripten')
+    if not os.path.exists(em_config_file):
+        raise RuntimeError("Emscripten configuration file '%s' does not exist" % em_config_file)
+    with open(em_config_file) as f:
+        em_config = {}
+        try:
+            # Emscripten configuration file is a Python file with simple assignments.
+            exec(f.read(), em_config)
+        except StandardError as e:
+            raise RuntimeError("Emscripten configuration file '%s' is invalid:\n%s" % (em_config_file, e))
+    if 'EMSCRIPTEN_ROOT' not in em_config:
+        raise RuntimeError("'EMSCRIPTEN_ROOT' missing in Emscripten configuration file '%s'" % em_config_file)
+    env.PrependENVPath('PATH', em_config['EMSCRIPTEN_ROOT'])
+
+    env['CC'] = 'emcc'
+    env['CXX'] = 'em++'
+    env['LINK'] = 'emcc'
+
+    # Emscripten's ar has issues with duplicate file names, so use cc.
+    env['AR'] = 'emcc'
+    env['ARFLAGS'] = '-o'
+    # emranlib is a noop, so it's safe to use with AR=emcc.
+    env['RANLIB'] = 'emranlib'
+
+    # Use TempFileMunge since some AR invocations are too long for cmd.exe.
+    # Use POSIX-style paths, required with TempFileMunge.
+    env['ARCOM_POSIX'] = env['ARCOM'].replace(
+        '$TARGET', '$TARGET.posix').replace(
+        '$SOURCES', '$SOURCES.posix')
+    env['ARCOM'] = '${TEMPFILE(ARCOM_POSIX)}'
+
+    # All intermediate files are just LLVM bitcode.
+    env['OBJPREFIX'] = ''
     env['OBJSUFFIX'] = '.bc'
+    env['PROGPREFIX'] = ''
+    # Program() output consists of multiple files, so specify suffixes manually at builder.
+    env['PROGSUFFIX'] = ''
+    env['LIBPREFIX'] = 'lib'
     env['LIBSUFFIX'] = '.bc'
+    env['LIBPREFIXES'] = ['$LIBPREFIX']
+    env['LIBSUFFIXES'] = ['$LIBSUFFIX']
 
     ## Compile flags
 
     env.Append(CPPPATH=['#platform/javascript'])
-    env.Append(CPPFLAGS=['-DJAVASCRIPT_ENABLED', '-DUNIX_ENABLED', '-DPTHREAD_NO_RENAME', '-DTYPED_METHOD_BIND', '-DNO_THREADS'])
-    env.Append(CPPFLAGS=['-DGLES3_ENABLED'])
+    env.Append(CPPDEFINES=['JAVASCRIPT_ENABLED', 'UNIX_ENABLED'])
 
-    # These flags help keep the file size down
-    env.Append(CPPFLAGS=["-fno-exceptions", '-DNO_SAFE_CAST', '-fno-rtti'])
+    # No multi-threading (SharedArrayBuffer) available yet,
+    # once feasible also consider memory buffer size issues.
+    env.Append(CPPDEFINES=['NO_THREADS'])
+
+    # These flags help keep the file size down.
+    env.Append(CCFLAGS=['-fno-exceptions', '-fno-rtti'])
+    # Don't use dynamic_cast, necessary with no-rtti.
+    env.Append(CPPDEFINES=['NO_SAFE_CAST'])
 
     if env['javascript_eval']:
-        env.Append(CPPFLAGS=['-DJAVASCRIPT_EVAL_ENABLED'])
+        env.Append(CPPDEFINES=['JAVASCRIPT_EVAL_ENABLED'])
 
     ## Link flags
 
     env.Append(LINKFLAGS=['-s', 'BINARYEN=1'])
+
+    # Allow increasing memory buffer size during runtime. This is efficient
+    # when using WebAssembly (in comparison to asm.js) and works well for
+    # us since we don't know requirements at compile-time.
     env.Append(LINKFLAGS=['-s', 'ALLOW_MEMORY_GROWTH=1'])
+
+    # This setting just makes WebGL 2 APIs available, it does NOT disable WebGL 1.
     env.Append(LINKFLAGS=['-s', 'USE_WEBGL2=1'])
-    env.Append(LINKFLAGS=['-s', 'EXTRA_EXPORTED_RUNTIME_METHODS="[\'FS\']"'])
 
     env.Append(LINKFLAGS=['-s', 'INVOKE_RUN=0'])
+
+    # TODO: Reevaluate usage of this setting now that engine.js manages engine runtime.
     env.Append(LINKFLAGS=['-s', 'NO_EXIT_RUNTIME=1'])
 
-    # TODO: Move that to opus module's config
+    # TODO: Move that to opus module's config.
     if 'module_opus_enabled' in env and env['module_opus_enabled']:
-        env.opus_fixed_point = "yes"
+        env.opus_fixed_point = 'yes'
diff --git a/platform/javascript/engine.js b/platform/javascript/engine.js
index bca1851f40..c3ef5bbbb5 100644
--- a/platform/javascript/engine.js
+++ b/platform/javascript/engine.js
@@ -1,3 +1,5 @@
+		exposedLibs['PATH'] = PATH;
+		exposedLibs['FS'] = FS;
 		return Module;
 	},
 };
@@ -8,10 +10,18 @@
 	var DOWNLOAD_ATTEMPTS_MAX = 4;
 
 	var basePath = null;
+	var wasmFilenameExtensionOverride = null;
 	var engineLoadPromise = null;
 
 	var loadingFiles = {};
 
+	function getPathLeaf(path) {
+
+		while (path.endsWith('/'))
+			path = path.slice(0, -1);
+		return path.slice(path.lastIndexOf('/') + 1);
+	}
+
 	function getBasePath(path) {
 
 		if (path.endsWith('/'))
@@ -23,14 +33,15 @@
 
 	function getBaseName(path) {
 
-		path = getBasePath(path);
-		return path.slice(path.lastIndexOf('/') + 1);
+		return getPathLeaf(getBasePath(path));
 	}
 
 	Engine = function Engine() {
 
 		this.rtenv = null;
 
+		var LIBS = {};
+
 		var initPromise = null;
 		var unloadAfterInit = true;
 
@@ -80,11 +91,11 @@
 			return new Promise(function(resolve, reject) {
 				rtenvProps.onRuntimeInitialized = resolve;
 				rtenvProps.onAbort = reject;
-				rtenvProps.engine.rtenv = Engine.RuntimeEnvironment(rtenvProps);
+				rtenvProps.engine.rtenv = Engine.RuntimeEnvironment(rtenvProps, LIBS);
 			});
 		}
 
-		this.preloadFile = function(pathOrBuffer, bufferFilename) {
+		this.preloadFile = function(pathOrBuffer, destPath) {
 
 			if (pathOrBuffer instanceof ArrayBuffer) {
 				pathOrBuffer = new Uint8Array(pathOrBuffer);
@@ -93,14 +104,14 @@
 			}
 			if (pathOrBuffer instanceof Uint8Array) {
 				preloadedFiles.push({
-					name: bufferFilename,
+					path: destPath,
 					buffer: pathOrBuffer
 				});
 				return Promise.resolve();
 			} else if (typeof pathOrBuffer === 'string') {
 				return loadPromise(pathOrBuffer, preloadProgressTracker).then(function(xhr) {
 					preloadedFiles.push({
-						name: pathOrBuffer,
+						path: destPath || pathOrBuffer,
 						buffer: xhr.response
 					});
 				});
@@ -119,8 +130,17 @@
 		this.startGame = function(mainPack) {
 
 			executableName = getBaseName(mainPack);
-			return Promise.all([this.init(getBasePath(mainPack)), this.preloadFile(mainPack)]).then(
-				Function.prototype.apply.bind(synchronousStart, this, [])
+			var mainArgs = [];
+			if (!getPathLeaf(mainPack).endsWith('.pck')) {
+				mainArgs = ['--main-pack', getPathLeaf(mainPack)];
+			}
+			return Promise.all([
+				// Load from directory,
+				this.init(getBasePath(mainPack)),
+				// ...but write to root where the engine expects it.
+				this.preloadFile(mainPack, getPathLeaf(mainPack))
+			]).then(
+				Function.prototype.apply.bind(synchronousStart, this, mainArgs)
 			);
 		};
 
@@ -138,18 +158,6 @@
 			}
 
 			var actualCanvas = this.rtenv.canvas;
-			var testContext = false;
-			var testCanvas;
-			try {
-				testCanvas = document.createElement('canvas');
-				testContext = testCanvas.getContext('webgl2') || testCanvas.getContext('experimental-webgl2');
-			} catch (e) {}
-			if (!testContext) {
-				throw new Error("WebGL 2 not available");
-			}
-			testCanvas = null;
-			testContext = null;
-
 			// canvas can grab focus on click
 			if (actualCanvas.tabIndex < 0) {
 				actualCanvas.tabIndex = 0;
@@ -158,6 +166,10 @@
 			actualCanvas.style.padding = 0;
 			actualCanvas.style.borderWidth = 0;
 			actualCanvas.style.borderStyle = 'none';
+			// disable right-click context menu
+			actualCanvas.addEventListener('contextmenu', function(ev) {
+				ev.preventDefault();
+			}, false);
 			// until context restoration is implemented
 			actualCanvas.addEventListener('webglcontextlost', function(ev) {
 				alert("WebGL context lost, please reload the page");
@@ -175,7 +187,16 @@
 			this.rtenv.thisProgram = executableName || getBaseName(basePath);
 
 			preloadedFiles.forEach(function(file) {
-				this.rtenv.FS.createDataFile('/', file.name, new Uint8Array(file.buffer), true, true, true);
+				var dir = LIBS.PATH.dirname(file.path);
+				try {
+					LIBS.FS.stat(dir);
+				} catch (e) {
+					if (e.code !== 'ENOENT') {
+						throw e;
+					}
+					LIBS.FS.mkdirTree(dir);
+				}
+				LIBS.FS.createDataFile('/', file.path, new Uint8Array(file.buffer), true, true, true);
 			}, this);
 
 			preloadedFiles = null;
@@ -273,6 +294,28 @@
 
 	Engine.RuntimeEnvironment = engine.RuntimeEnvironment;
 
+	Engine.isWebGLAvailable = function(majorVersion = 1) {
+
+		var testContext = false;
+		try {
+			var testCanvas = document.createElement('canvas');
+			if (majorVersion === 1) {
+				testContext = testCanvas.getContext('webgl') || testCanvas.getContext('experimental-webgl');
+			} else if (majorVersion === 2) {
+				testContext = testCanvas.getContext('webgl2') || testCanvas.getContext('experimental-webgl2');
+			}
+		} catch (e) {}
+		return !!testContext;
+	};
+
+	Engine.setWebAssemblyFilenameExtension = function(override) {
+
+		if (String(override).length === 0) {
+			throw new Error('Invalid WebAssembly filename extension override');
+		}
+		wasmFilenameExtensionOverride = String(override);
+	}
+
 	Engine.load = function(newBasePath) {
 
 		if (newBasePath !== undefined) basePath = getBasePath(newBasePath);
@@ -280,7 +323,7 @@
 			if (typeof WebAssembly !== 'object')
 				return Promise.reject(new Error("Browser doesn't support WebAssembly"));
 			// TODO cache/retrieve module to/from idb
-			engineLoadPromise = loadPromise(basePath + '.wasm').then(function(xhr) {
+			engineLoadPromise = loadPromise(basePath + '.' + (wasmFilenameExtensionOverride || 'wasm')).then(function(xhr) {
 				return xhr.response;
 			});
 			engineLoadPromise = engineLoadPromise.catch(function(err) {
diff --git a/platform/javascript/export/export.cpp b/platform/javascript/export/export.cpp
index d81aa25c32..9591850662 100644
--- a/platform/javascript/export/export.cpp
+++ b/platform/javascript/export/export.cpp
@@ -117,7 +117,7 @@ void EditorExportPlatformJavaScript::get_export_options(List<ExportOption> *r_op
 	r_options->push_back(ExportOption(PropertyInfo(Variant::BOOL, "texture_format/s3tc"), true));
 	r_options->push_back(ExportOption(PropertyInfo(Variant::BOOL, "texture_format/etc"), false));
 	r_options->push_back(ExportOption(PropertyInfo(Variant::BOOL, "texture_format/etc2"), true));
-	r_options->push_back(ExportOption(PropertyInfo(Variant::STRING, "html/custom_html_shell", PROPERTY_HINT_GLOBAL_FILE, "html"), ""));
+	r_options->push_back(ExportOption(PropertyInfo(Variant::STRING, "html/custom_html_shell", PROPERTY_HINT_FILE, "html"), ""));
 	r_options->push_back(ExportOption(PropertyInfo(Variant::STRING, "html/head_include", PROPERTY_HINT_MULTILINE_TEXT), ""));
 	r_options->push_back(ExportOption(PropertyInfo(Variant::STRING, "custom_template/release", PROPERTY_HINT_GLOBAL_FILE, "zip"), ""));
 	r_options->push_back(ExportOption(PropertyInfo(Variant::STRING, "custom_template/debug", PROPERTY_HINT_GLOBAL_FILE, "zip"), ""));
diff --git a/platform/javascript/http_client.h.inc b/platform/javascript/http_client.h.inc
index 23a74e68f5..d75d33a33a 100644
--- a/platform/javascript/http_client.h.inc
+++ b/platform/javascript/http_client.h.inc
@@ -46,3 +46,8 @@ String password;
 int polled_response_code;
 String polled_response_header;
 PoolByteArray polled_response;
+
+#ifdef DEBUG_ENABLED
+bool has_polled;
+uint64_t last_polling_frame;
+#endif
diff --git a/platform/javascript/http_client_javascript.cpp b/platform/javascript/http_client_javascript.cpp
index 1cd2719723..8d90e01ae1 100644
--- a/platform/javascript/http_client_javascript.cpp
+++ b/platform/javascript/http_client_javascript.cpp
@@ -81,12 +81,14 @@ Ref<StreamPeer> HTTPClient::get_connection() const {
 Error HTTPClient::prepare_request(Method p_method, const String &p_url, const Vector<String> &p_headers) {
 
 	ERR_FAIL_INDEX_V(p_method, METHOD_MAX, ERR_INVALID_PARAMETER);
+	ERR_EXPLAIN("HTTP methods TRACE and CONNECT are not supported for the HTML5 platform");
+	ERR_FAIL_COND_V(p_method == METHOD_TRACE || p_method == METHOD_CONNECT, ERR_UNAVAILABLE);
 	ERR_FAIL_COND_V(status != STATUS_CONNECTED, ERR_INVALID_PARAMETER);
 	ERR_FAIL_COND_V(host.empty(), ERR_UNCONFIGURED);
 	ERR_FAIL_COND_V(port < 0, ERR_UNCONFIGURED);
 	ERR_FAIL_COND_V(!p_url.begins_with("/"), ERR_INVALID_PARAMETER);
 
-	String url = (use_tls ? "https://" : "http://") + host + ":" + itos(port) + "/" + p_url;
+	String url = (use_tls ? "https://" : "http://") + host + ":" + itos(port) + p_url;
 	godot_xhr_reset(xhr_id);
 	godot_xhr_open(xhr_id, _methods[p_method], url.utf8().get_data(),
 			username.empty() ? NULL : username.utf8().get_data(),
@@ -158,7 +160,7 @@ int HTTPClient::get_response_code() const {
 
 Error HTTPClient::get_response_headers(List<String> *r_response) {
 
-	if (!polled_response_header.size())
+	if (polled_response_header.empty())
 		return ERR_INVALID_PARAMETER;
 
 	Vector<String> header_lines = polled_response_header.split("\r\n", false);
@@ -191,8 +193,6 @@ PoolByteArray HTTPClient::read_response_body_chunk() {
 	if (response_read_offset == polled_response.size()) {
 		status = STATUS_CONNECTED;
 		polled_response.resize(0);
-		polled_response_code = 0;
-		polled_response_header = String();
 		godot_xhr_reset(xhr_id);
 	}
 
@@ -238,34 +238,47 @@ Error HTTPClient::poll() {
 			return ERR_CONNECTION_ERROR;
 
 		case STATUS_REQUESTING:
-			polled_response_code = godot_xhr_get_status(xhr_id);
-			int response_length = godot_xhr_get_response_length(xhr_id);
-			if (response_length == 0) {
-				godot_xhr_ready_state_t ready_state = godot_xhr_get_ready_state(xhr_id);
-				if (ready_state == XHR_READY_STATE_HEADERS_RECEIVED || ready_state == XHR_READY_STATE_LOADING) {
-					return OK;
-				} else {
-					status = STATUS_CONNECTION_ERROR;
-					return ERR_CONNECTION_ERROR;
+
+#ifdef DEBUG_ENABLED
+			if (!has_polled) {
+				has_polled = true;
+			} else {
+				// forcing synchronous requests is not possible on the web
+				if (last_polling_frame == Engine::get_singleton()->get_idle_frames()) {
+					WARN_PRINT("HTTPClient polled multiple times in one frame, "
+							   "but request cannot progress more than once per "
+							   "frame on the HTML5 platform.");
 				}
 			}
+			last_polling_frame = Engine::get_singleton()->get_idle_frames();
+#endif
+
+			polled_response_code = godot_xhr_get_status(xhr_id);
+			if (godot_xhr_get_ready_state(xhr_id) != XHR_READY_STATE_DONE) {
+				return OK;
+			} else if (!polled_response_code) {
+				status = STATUS_CONNECTION_ERROR;
+				return ERR_CONNECTION_ERROR;
+			}
 
 			status = STATUS_BODY;
 
 			PoolByteArray bytes;
 			int len = godot_xhr_get_response_headers_length(xhr_id);
-			bytes.resize(len);
+			bytes.resize(len + 1);
+
 			PoolByteArray::Write write = bytes.write();
 			godot_xhr_get_response_headers(xhr_id, reinterpret_cast<char *>(write.ptr()), len);
+			write[len] = 0;
 			write = PoolByteArray::Write();
 
 			PoolByteArray::Read read = bytes.read();
 			polled_response_header = String::utf8(reinterpret_cast<const char *>(read.ptr()));
 			read = PoolByteArray::Read();
 
-			polled_response.resize(response_length);
+			polled_response.resize(godot_xhr_get_response_length(xhr_id));
 			write = polled_response.write();
-			godot_xhr_get_response(xhr_id, write.ptr(), response_length);
+			godot_xhr_get_response(xhr_id, write.ptr(), polled_response.size());
 			write = PoolByteArray::Write();
 			break;
 	}
@@ -280,6 +293,10 @@ HTTPClient::HTTPClient() {
 	port = -1;
 	use_tls = false;
 	polled_response_code = 0;
+#ifdef DEBUG_ENABLED
+	has_polled = false;
+	last_polling_frame = 0;
+#endif
 }
 
 HTTPClient::~HTTPClient() {
diff --git a/platform/javascript/javascript_main.cpp b/platform/javascript/javascript_main.cpp
index e85fe0800f..68a2d72464 100644
--- a/platform/javascript/javascript_main.cpp
+++ b/platform/javascript/javascript_main.cpp
@@ -40,7 +40,7 @@ static void main_loop() {
 	os->main_loop_iterate();
 }
 
-extern "C" void main_after_fs_sync(char *p_idbfs_err) {
+extern "C" EMSCRIPTEN_KEEPALIVE void main_after_fs_sync(char *p_idbfs_err) {
 
 	String idbfs_err = String::utf8(p_idbfs_err);
 	if (!idbfs_err.empty()) {
@@ -56,8 +56,6 @@ extern "C" void main_after_fs_sync(char *p_idbfs_err) {
 
 int main(int argc, char *argv[]) {
 
-	printf("let it go dude!\n");
-
 	// sync from persistent state into memory and then
 	// run the 'main_after_fs_sync' function
 	/* clang-format off */
diff --git a/platform/javascript/logo.png b/platform/javascript/logo.png
index ce911180ac..36832d93ba 100644
--- a/platform/javascript/logo.png
+++ b/platform/javascript/logo.png
diff --git a/platform/javascript/os_javascript.cpp b/platform/javascript/os_javascript.cpp
index e226ab6332..6c6e4d2d1c 100644
--- a/platform/javascript/os_javascript.cpp
+++ b/platform/javascript/os_javascript.cpp
@@ -33,6 +33,7 @@
 #include "core/engine.h"
 #include "core/io/file_access_buffered_fa.h"
 #include "dom_keys.h"
+#include "drivers/gles2/rasterizer_gles2.h"
 #include "drivers/gles3/rasterizer_gles3.h"
 #include "drivers/unix/dir_access_unix.h"
 #include "drivers/unix/file_access_unix.h"
@@ -57,12 +58,19 @@ static void dom2godot_mod(T emscripten_event_ptr, Ref<InputEventWithModifiers> g
 
 int OS_JavaScript::get_video_driver_count() const {
 
-	return 1;
+	return VIDEO_DRIVER_MAX;
 }
 
 const char *OS_JavaScript::get_video_driver_name(int p_driver) const {
 
-	return "GLES3";
+	switch (p_driver) {
+		case VIDEO_DRIVER_GLES3:
+			return "GLES3";
+		case VIDEO_DRIVER_GLES2:
+			return "GLES2";
+	}
+	ERR_EXPLAIN("Invalid video driver index " + itos(p_driver));
+	ERR_FAIL_V(NULL);
 }
 
 int OS_JavaScript::get_audio_driver_count() const {
@@ -159,10 +167,9 @@ static EM_BOOL _mousebutton_callback(int event_type, const EmscriptenMouseEvent
 	int mask = _input->get_mouse_button_mask();
 	int button_flag = 1 << (ev->get_button_index() - 1);
 	if (ev->is_pressed()) {
-		// since the event is consumed, focus manually
-		if (!is_canvas_focused()) {
-			focus_canvas();
-		}
+		// Since the event is consumed, focus manually. The containing iframe,
+		// if used, may not have focus yet, so focus even if already focused.
+		focus_canvas();
 		mask |= button_flag;
 	} else if (mask & button_flag) {
 		mask &= ~button_flag;
@@ -173,7 +180,8 @@ static EM_BOOL _mousebutton_callback(int event_type, const EmscriptenMouseEvent
 	ev->set_button_mask(mask);
 
 	_input->parse_input_event(ev);
-	// prevent selection dragging
+	// Prevent multi-click text selection and wheel-click scrolling anchor.
+	// Context menu is prevented through contextmenu event.
 	return true;
 }
 
@@ -196,7 +204,7 @@ static EM_BOOL _mousemove_callback(int event_type, const EmscriptenMouseEvent *m
 	ev->set_position(pos);
 	ev->set_global_position(ev->get_position());
 
-	ev->set_relative(ev->get_position() - _input->get_mouse_position());
+	ev->set_relative(Vector2(mouse_event->movementX, mouse_event->movementY));
 	_input->set_mouse_position(ev->get_position());
 	ev->set_speed(_input->get_last_mouse_speed());
 
@@ -277,23 +285,6 @@ static EM_BOOL _touchpress_callback(int event_type, const EmscriptenTouchEvent *
 
 		_input->parse_input_event(ev);
 	}
-
-	if (touch_event->touches[lowest_id_index].isChanged) {
-
-		Ref<InputEventMouseButton> ev_mouse;
-		ev_mouse.instance();
-		ev_mouse->set_button_mask(_input->get_mouse_button_mask());
-		dom2godot_mod(touch_event, ev_mouse);
-
-		const EmscriptenTouchPoint &first_touch = touch_event->touches[lowest_id_index];
-		ev_mouse->set_position(Point2(first_touch.canvasX, first_touch.canvasY));
-		ev_mouse->set_global_position(ev_mouse->get_position());
-
-		ev_mouse->set_button_index(BUTTON_LEFT);
-		ev_mouse->set_pressed(event_type == EMSCRIPTEN_EVENT_TOUCHSTART);
-
-		_input->parse_input_event(ev_mouse);
-	}
 	return true;
 }
 
@@ -319,24 +310,6 @@ static EM_BOOL _touchmove_callback(int event_type, const EmscriptenTouchEvent *t
 
 		_input->parse_input_event(ev);
 	}
-
-	if (touch_event->touches[lowest_id_index].isChanged) {
-
-		Ref<InputEventMouseMotion> ev_mouse;
-		ev_mouse.instance();
-		dom2godot_mod(touch_event, ev_mouse);
-		ev_mouse->set_button_mask(_input->get_mouse_button_mask());
-
-		const EmscriptenTouchPoint &first_touch = touch_event->touches[lowest_id_index];
-		ev_mouse->set_position(Point2(first_touch.canvasX, first_touch.canvasY));
-		ev_mouse->set_global_position(ev_mouse->get_position());
-
-		ev_mouse->set_relative(ev_mouse->get_position() - _input->get_mouse_position());
-		_input->set_mouse_position(ev_mouse->get_position());
-		ev_mouse->set_speed(_input->get_last_mouse_speed());
-
-		_input->parse_input_event(ev_mouse);
-	}
 	return true;
 }
 
@@ -405,14 +378,13 @@ static EM_BOOL joy_callback_func(int p_type, const EmscriptenGamepadEvent *p_eve
 	return false;
 }
 
-extern "C" {
-void send_notification(int notif) {
+extern "C" EMSCRIPTEN_KEEPALIVE void send_notification(int notif) {
+
 	if (notif == MainLoop::NOTIFICATION_WM_MOUSE_ENTER || notif == MainLoop::NOTIFICATION_WM_MOUSE_EXIT) {
 		_cursor_inside_canvas = notif == MainLoop::NOTIFICATION_WM_MOUSE_ENTER;
 	}
 	OS_JavaScript::get_singleton()->get_main_loop()->notification(notif);
 }
-}
 
 Error OS_JavaScript::initialize(const VideoMode &p_desired, int p_video_driver, int p_audio_driver) {
 
@@ -422,8 +394,21 @@ Error OS_JavaScript::initialize(const VideoMode &p_desired, int p_video_driver,
 	emscripten_webgl_init_context_attributes(&attributes);
 	attributes.alpha = false;
 	attributes.antialias = false;
-	attributes.majorVersion = 2;
+	ERR_FAIL_INDEX_V(p_video_driver, VIDEO_DRIVER_MAX, ERR_INVALID_PARAMETER);
+	switch (p_video_driver) {
+		case VIDEO_DRIVER_GLES3:
+			attributes.majorVersion = 2;
+			RasterizerGLES3::register_config();
+			RasterizerGLES3::make_current();
+			break;
+		case VIDEO_DRIVER_GLES2:
+			attributes.majorVersion = 1;
+			RasterizerGLES2::register_config();
+			RasterizerGLES2::make_current();
+			break;
+	}
 	EMSCRIPTEN_WEBGL_CONTEXT_HANDLE ctx = emscripten_webgl_create_context(NULL, &attributes);
+	ERR_EXPLAIN("WebGL " + itos(attributes.majorVersion) + ".0 not available");
 	ERR_FAIL_COND_V(emscripten_webgl_make_context_current(ctx) != EMSCRIPTEN_RESULT_SUCCESS, ERR_UNAVAILABLE);
 
 	video_mode = p_desired;
@@ -447,12 +432,8 @@ Error OS_JavaScript::initialize(const VideoMode &p_desired, int p_video_driver,
 
 	print_line("Init Audio");
 
-	AudioDriverManager::add_driver(&audio_driver_javascript);
 	AudioDriverManager::initialize(p_audio_driver);
 
-	RasterizerGLES3::register_config();
-	RasterizerGLES3::make_current();
-
 	print_line("Init VS");
 
 	visual_server = memnew(VisualServerRaster());
@@ -463,8 +444,6 @@ Error OS_JavaScript::initialize(const VideoMode &p_desired, int p_video_driver,
 	input = memnew(InputDefault);
 	_input = input;
 
-	power_manager = memnew(PowerJavascript);
-
 #define EM_CHECK(ev)                         \
 	if (result != EMSCRIPTEN_RESULT_SUCCESS) \
 	ERR_PRINTS("Error while setting " #ev " callback: Code " + itos(result))
@@ -951,15 +930,21 @@ String OS_JavaScript::get_joy_guid(int p_device) const {
 }
 
 OS::PowerState OS_JavaScript::get_power_state() {
-	return power_manager->get_power_state();
+
+	WARN_PRINT("Power management is not supported for the HTML5 platform, defaulting to POWERSTATE_UNKNOWN");
+	return OS::POWERSTATE_UNKNOWN;
 }
 
 int OS_JavaScript::get_power_seconds_left() {
-	return power_manager->get_power_seconds_left();
+
+	WARN_PRINT("Power management is not supported for the HTML5 platform, defaulting to -1");
+	return -1;
 }
 
 int OS_JavaScript::get_power_percent_left() {
-	return power_manager->get_power_percent_left();
+
+	WARN_PRINT("Power management is not supported for the HTML5 platform, defaulting to -1");
+	return -1;
 }
 
 bool OS_JavaScript::_check_internal_feature_support(const String &p_feature) {
@@ -1012,6 +997,8 @@ OS_JavaScript::OS_JavaScript(const char *p_execpath, GetUserDataDirFunc p_get_us
 	Vector<Logger *> loggers;
 	loggers.push_back(memnew(StdLogger));
 	_set_logger(memnew(CompositeLogger(loggers)));
+
+	AudioDriverManager::add_driver(&audio_driver_javascript);
 }
 
 OS_JavaScript::~OS_JavaScript() {
diff --git a/platform/javascript/os_javascript.h b/platform/javascript/os_javascript.h
index f0ba9422e8..46eb1b3f13 100644
--- a/platform/javascript/os_javascript.h
+++ b/platform/javascript/os_javascript.h
@@ -36,7 +36,6 @@
 #include "main/input_default.h"
 #include "os/input.h"
 #include "os/main_loop.h"
-#include "power_javascript.h"
 #include "servers/audio_server.h"
 #include "servers/visual/rasterizer.h"
 
@@ -64,8 +63,6 @@ class OS_JavaScript : public OS_Unix {
 
 	GetUserDataDirFunc get_user_data_dir_func;
 
-	PowerJavascript *power_manager;
-
 	static void _close_notification_funcs(const String &p_file, int p_flags);
 
 	void process_joypads();
diff --git a/platform/javascript/power_javascript.cpp b/platform/javascript/power_javascript.cpp
deleted file mode 100644
index 5241644dbc..0000000000
--- a/platform/javascript/power_javascript.cpp
+++ /dev/null
@@ -1,73 +0,0 @@
-/*************************************************************************/
-/*  power_javascript.cpp                                                 */
-/*************************************************************************/
-/*                       This file is part of:                           */
-/*                           GODOT ENGINE                                */
-/*                      https://godotengine.org                          */
-/*************************************************************************/
-/* Copyright (c) 2007-2018 Juan Linietsky, Ariel Manzur.                 */
-/* Copyright (c) 2014-2018 Godot Engine contributors (cf. AUTHORS.md)    */
-/*                                                                       */
-/* Permission is hereby granted, free of charge, to any person obtaining */
-/* a copy of this software and associated documentation files (the       */
-/* "Software"), to deal in the Software without restriction, including   */
-/* without limitation the rights to use, copy, modify, merge, publish,   */
-/* distribute, sublicense, and/or sell copies of the Software, and to    */
-/* permit persons to whom the Software is furnished to do so, subject to */
-/* the following conditions:                                             */
-/*                                                                       */
-/* The above copyright notice and this permission notice shall be        */
-/* included in all copies or substantial portions of the Software.       */
-/*                                                                       */
-/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
-/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
-/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
-/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
-/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
-/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
-/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
-/*************************************************************************/
-
-#include "power_javascript.h"
-#include "error_macros.h"
-
-bool PowerJavascript::UpdatePowerInfo() {
-	// TODO Javascript implementation
-	return false;
-}
-
-OS::PowerState PowerJavascript::get_power_state() {
-	if (UpdatePowerInfo()) {
-		return power_state;
-	} else {
-		WARN_PRINT("Power management is not implemented on this platform, defaulting to POWERSTATE_UNKNOWN");
-		return OS::POWERSTATE_UNKNOWN;
-	}
-}
-
-int PowerJavascript::get_power_seconds_left() {
-	if (UpdatePowerInfo()) {
-		return nsecs_left;
-	} else {
-		WARN_PRINT("Power management is not implemented on this platform, defaulting to -1");
-		return -1;
-	}
-}
-
-int PowerJavascript::get_power_percent_left() {
-	if (UpdatePowerInfo()) {
-		return percent_left;
-	} else {
-		WARN_PRINT("Power management is not implemented on this platform, defaulting to -1");
-		return -1;
-	}
-}
-
-PowerJavascript::PowerJavascript() :
-		nsecs_left(-1),
-		percent_left(-1),
-		power_state(OS::POWERSTATE_UNKNOWN) {
-}
-
-PowerJavascript::~PowerJavascript() {
-}
diff --git a/platform/javascript/power_javascript.h b/platform/javascript/power_javascript.h
deleted file mode 100644
index c0c564aa60..0000000000
--- a/platform/javascript/power_javascript.h
+++ /dev/null
@@ -1,53 +0,0 @@
-/*************************************************************************/
-/*  power_javascript.h                                                   */
-/*************************************************************************/
-/*                       This file is part of:                           */
-/*                           GODOT ENGINE                                */
-/*                      https://godotengine.org                          */
-/*************************************************************************/
-/* Copyright (c) 2007-2018 Juan Linietsky, Ariel Manzur.                 */
-/* Copyright (c) 2014-2018 Godot Engine contributors (cf. AUTHORS.md)    */
-/*                                                                       */
-/* Permission is hereby granted, free of charge, to any person obtaining */
-/* a copy of this software and associated documentation files (the       */
-/* "Software"), to deal in the Software without restriction, including   */
-/* without limitation the rights to use, copy, modify, merge, publish,   */
-/* distribute, sublicense, and/or sell copies of the Software, and to    */
-/* permit persons to whom the Software is furnished to do so, subject to */
-/* the following conditions:                                             */
-/*                                                                       */
-/* The above copyright notice and this permission notice shall be        */
-/* included in all copies or substantial portions of the Software.       */
-/*                                                                       */
-/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
-/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
-/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
-/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
-/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
-/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
-/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
-/*************************************************************************/
-
-#ifndef PLATFORM_JAVASCRIPT_POWER_JAVASCRIPT_H_
-#define PLATFORM_JAVASCRIPT_POWER_JAVASCRIPT_H_
-
-#include "os/os.h"
-
-class PowerJavascript {
-private:
-	int nsecs_left;
-	int percent_left;
-	OS::PowerState power_state;
-
-	bool UpdatePowerInfo();
-
-public:
-	PowerJavascript();
-	virtual ~PowerJavascript();
-
-	OS::PowerState get_power_state();
-	int get_power_seconds_left();
-	int get_power_percent_left();
-};
-
-#endif /* PLATFORM_JAVASCRIPT_POWER_JAVASCRIPT_H_ */
diff --git a/platform/javascript/pre.js b/platform/javascript/pre.js
index 311aa44fda..02194bc75e 100644
--- a/platform/javascript/pre.js
+++ b/platform/javascript/pre.js
@@ -1,2 +1,2 @@
 var Engine = {
-	RuntimeEnvironment: function(Module) {
+	RuntimeEnvironment: function(Module, exposedLibs) {
diff --git a/platform/javascript/run_icon.png b/platform/javascript/run_icon.png
index dedee6f479..574abb0150 100644
--- a/platform/javascript/run_icon.png
+++ b/platform/javascript/run_icon.png