12 files changed, 1661 insertions, 558 deletions

diff --git a/platform/javascript/js/engine/config.js b/platform/javascript/js/engine/config.js
new file mode 100644
index 0000000000..6072782875
--- /dev/null
+++ b/platform/javascript/js/engine/config.js
@@ -0,0 +1,337 @@
+/**
+ * An object used to configure the Engine instance based on godot export options, and to override those in custom HTML
+ * templates if needed.
+ *
+ * @header Engine configuration
+ * @summary The Engine configuration object. This is just a typedef, create it like a regular object, e.g.:
+ *
+ * ``const MyConfig = { executable: 'godot', unloadAfterInit: false }``
+ *
+ * @typedef {Object} EngineConfig
+ */
+const EngineConfig = {}; // eslint-disable-line no-unused-vars
+
+/**
+ * @struct
+ * @constructor
+ * @ignore
+ */
+const InternalConfig = function (initConfig) { // eslint-disable-line no-unused-vars
+	const cfg = /** @lends {InternalConfig.prototype} */ {
+		/**
+		 * Whether the unload the engine automatically after the instance is initialized.
+		 *
+		 * @memberof EngineConfig
+		 * @default
+		 * @type {boolean}
+		 */
+		unloadAfterInit: true,
+		/**
+		 * The HTML DOM Canvas object to use.
+		 *
+		 * By default, the first canvas element in the document will be used is none is specified.
+		 *
+		 * @memberof EngineConfig
+		 * @default
+		 * @type {?HTMLCanvasElement}
+		 */
+		canvas: null,
+		/**
+		 * The name of the WASM file without the extension. (Set by Godot Editor export process).
+		 *
+		 * @memberof EngineConfig
+		 * @default
+		 * @type {string}
+		 */
+		executable: '',
+		/**
+		 * An alternative name for the game pck to load. The executable name is used otherwise.
+		 *
+		 * @memberof EngineConfig
+		 * @default
+		 * @type {?string}
+		 */
+		mainPack: null,
+		/**
+		 * Specify a language code to select the proper localization for the game.
+		 *
+		 * The browser locale will be used if none is specified. See complete list of
+		 * :ref:`supported locales <doc_locales>`.
+		 *
+		 * @memberof EngineConfig
+		 * @type {?string}
+		 * @default
+		 */
+		locale: null,
+		/**
+		 * The canvas resize policy determines how the canvas should be resized by Godot.
+		 *
+		 * ``0`` means Godot won't do any resizing. This is useful if you want to control the canvas size from
+		 * javascript code in your template.
+		 *
+		 * ``1`` means Godot will resize the canvas on start, and when changing window size via engine functions.
+		 *
+		 * ``2`` means Godot will adapt the canvas size to match the whole browser window.
+		 *
+		 * @memberof EngineConfig
+		 * @type {number}
+		 * @default
+		 */
+		canvasResizePolicy: 2,
+		/**
+		 * The arguments to be passed as command line arguments on startup.
+		 *
+		 * See :ref:`command line tutorial <doc_command_line_tutorial>`.
+		 *
+		 * **Note**: :js:meth:`startGame <Engine.prototype.startGame>` will always add the ``--main-pack`` argument.
+		 *
+		 * @memberof EngineConfig
+		 * @type {Array<string>}
+		 * @default
+		 */
+		args: [],
+		/**
+		 * When enabled, this will turn on experimental virtual keyboard support on mobile.
+		 *
+		 * @memberof EngineConfig
+		 * @type {boolean}
+		 * @default
+		 */
+		experimentalVK: false,
+		/**
+		 * @ignore
+		 * @type {Array.<string>}
+		 */
+		persistentPaths: ['/userfs'],
+		/**
+		 * @ignore
+		 * @type {boolean}
+		 */
+		persistentDrops: false,
+		/**
+		 * @ignore
+		 * @type {Array.<string>}
+		 */
+		gdnativeLibs: [],
+		/**
+		 * @ignore
+		 * @type {Array.<string>}
+		 */
+		fileSizes: [],
+		/**
+		 * A callback function for handling Godot's ``OS.execute`` calls.
+		 *
+		 * This is for example used in the Web Editor template to switch between project manager and editor, and for running the game.
+		 *
+		 * @callback EngineConfig.onExecute
+		 * @param {string} path The path that Godot's wants executed.
+		 * @param {Array.<string>} args The arguments of the "command" to execute.
+		 */
+		/**
+		 * @ignore
+		 * @type {?function(string, Array.<string>)}
+		 */
+		onExecute: null,
+		/**
+		 * A callback function for being notified when the Godot instance quits.
+		 *
+		 * **Note**: This function will not be called if the engine crashes or become unresponsive.
+		 *
+		 * @callback EngineConfig.onExit
+		 * @param {number} status_code The status code returned by Godot on exit.
+		 */
+		/**
+		 * @ignore
+		 * @type {?function(number)}
+		 */
+		onExit: null,
+		/**
+		 * A callback function for displaying download progress.
+		 *
+		 * The function is called once per frame while downloading files, so the usage of ``requestAnimationFrame()``
+		 * is not necessary.
+		 *
+		 * If the callback function receives a total amount of bytes as 0, this means that it is impossible to calculate.
+		 * Possible reasons include:
+		 *
+		 * -  Files are delivered with server-side chunked compression
+		 * -  Files are delivered with server-side compression on Chromium
+		 * -  Not all file downloads have started yet (usually on servers without multi-threading)
+		 *
+		 * @callback EngineConfig.onProgress
+		 * @param {number} current The current amount of downloaded bytes so far.
+		 * @param {number} total The total amount of bytes to be downloaded.
+		 */
+		/**
+		 * @ignore
+		 * @type {?function(number, number)}
+		 */
+		onProgress: null,
+		/**
+		 * A callback function for handling the standard output stream. This method should usually only be used in debug pages.
+		 *
+		 * By default, ``console.log()`` is used.
+		 *
+		 * @callback EngineConfig.onPrint
+		 * @param {...*} [var_args] A variadic number of arguments to be printed.
+		 */
+		/**
+		 * @ignore
+		 * @type {?function(...*)}
+		 */
+		onPrint: function () {
+			console.log.apply(console, Array.from(arguments)); // eslint-disable-line no-console
+		},
+		/**
+		 * A callback function for handling the standard error stream. This method should usually only be used in debug pages.
+		 *
+		 * By default, ``console.error()`` is used.
+		 *
+		 * @callback EngineConfig.onPrintError
+		 * @param {...*} [var_args] A variadic number of arguments to be printed as errors.
+		*/
+		/**
+		 * @ignore
+		 * @type {?function(...*)}
+		 */
+		onPrintError: function (var_args) {
+			console.error.apply(console, Array.from(arguments)); // eslint-disable-line no-console
+		},
+	};
+
+	/**
+	 * @ignore
+	 * @struct
+	 * @constructor
+	 * @param {EngineConfig} opts
+	 */
+	function Config(opts) {
+		this.update(opts);
+	}
+
+	Config.prototype = cfg;
+
+	/**
+	 * @ignore
+	 * @param {EngineConfig} opts
+	 */
+	Config.prototype.update = function (opts) {
+		const config = opts || {};
+		function parse(key, def) {
+			if (typeof (config[key]) === 'undefined') {
+				return def;
+			}
+			return config[key];
+		}
+		// Module config
+		this.unloadAfterInit = parse('unloadAfterInit', this.unloadAfterInit);
+		this.onPrintError = parse('onPrintError', this.onPrintError);
+		this.onPrint = parse('onPrint', this.onPrint);
+		this.onProgress = parse('onProgress', this.onProgress);
+
+		// Godot config
+		this.canvas = parse('canvas', this.canvas);
+		this.executable = parse('executable', this.executable);
+		this.mainPack = parse('mainPack', this.mainPack);
+		this.locale = parse('locale', this.locale);
+		this.canvasResizePolicy = parse('canvasResizePolicy', this.canvasResizePolicy);
+		this.persistentPaths = parse('persistentPaths', this.persistentPaths);
+		this.persistentDrops = parse('persistentDrops', this.persistentDrops);
+		this.experimentalVK = parse('experimentalVK', this.experimentalVK);
+		this.gdnativeLibs = parse('gdnativeLibs', this.gdnativeLibs);
+		this.fileSizes = parse('fileSizes', this.fileSizes);
+		this.args = parse('args', this.args);
+		this.onExecute = parse('onExecute', this.onExecute);
+		this.onExit = parse('onExit', this.onExit);
+	};
+
+	/**
+	 * @ignore
+	 * @param {string} loadPath
+	 * @param {Response} response
+	 */
+	Config.prototype.getModuleConfig = function (loadPath, response) {
+		let r = response;
+		return {
+			'print': this.onPrint,
+			'printErr': this.onPrintError,
+			'thisProgram': this.executable,
+			'noExitRuntime': true,
+			'dynamicLibraries': [`${loadPath}.side.wasm`],
+			'instantiateWasm': function (imports, onSuccess) {
+				function done(result) {
+					onSuccess(result['instance'], result['module']);
+				}
+				if (typeof (WebAssembly.instantiateStreaming) !== 'undefined') {
+					WebAssembly.instantiateStreaming(Promise.resolve(r), imports).then(done);
+				} else {
+					r.arrayBuffer().then(function (buffer) {
+						WebAssembly.instantiate(buffer, imports).then(done);
+					});
+				}
+				r = null;
+				return {};
+			},
+			'locateFile': function (path) {
+				if (path.endsWith('.worker.js')) {
+					return `${loadPath}.worker.js`;
+				} else if (path.endsWith('.audio.worklet.js')) {
+					return `${loadPath}.audio.worklet.js`;
+				} else if (path.endsWith('.js')) {
+					return `${loadPath}.js`;
+				} else if (path.endsWith('.side.wasm')) {
+					return `${loadPath}.side.wasm`;
+				} else if (path.endsWith('.wasm')) {
+					return `${loadPath}.wasm`;
+				}
+				return path;
+			},
+		};
+	};
+
+	/**
+	 * @ignore
+	 * @param {function()} cleanup
+	 */
+	Config.prototype.getGodotConfig = function (cleanup) {
+		// Try to find a canvas
+		if (!(this.canvas instanceof HTMLCanvasElement)) {
+			const nodes = document.getElementsByTagName('canvas');
+			if (nodes.length && nodes[0] instanceof HTMLCanvasElement) {
+				this.canvas = nodes[0];
+			}
+			if (!this.canvas) {
+				throw new Error('No canvas found in page');
+			}
+		}
+		// Canvas can grab focus on click, or key events won't work.
+		if (this.canvas.tabIndex < 0) {
+			this.canvas.tabIndex = 0;
+		}
+
+		// Browser locale, or custom one if defined.
+		let locale = this.locale;
+		if (!locale) {
+			locale = navigator.languages ? navigator.languages[0] : navigator.language;
+			locale = locale.split('.')[0];
+		}
+		const onExit = this.onExit;
+
+		// Godot configuration.
+		return {
+			'canvas': this.canvas,
+			'canvasResizePolicy': this.canvasResizePolicy,
+			'locale': locale,
+			'persistentDrops': this.persistentDrops,
+			'virtualKeyboard': this.experimentalVK,
+			'onExecute': this.onExecute,
+			'onExit': function (p_code) {
+				cleanup(); // We always need to call the cleanup callback to free memory.
+				if (typeof (onExit) === 'function') {
+					onExit(p_code);
+				}
+			},
+		};
+	};
+	return new Config(initConfig);
+};
diff --git a/platform/javascript/js/engine/engine.externs.js b/platform/javascript/js/engine/engine.externs.js
index 1a94dd15ec..35a66a93ae 100644
--- a/platform/javascript/js/engine/engine.externs.js
+++ b/platform/javascript/js/engine/engine.externs.js
@@ -1,3 +1,4 @@
 var Godot;
 var WebAssembly = {};
 WebAssembly.instantiate = function(buffer, imports) {};
+WebAssembly.instantiateStreaming = function(response, imports) {};
diff --git a/platform/javascript/js/engine/engine.js b/platform/javascript/js/engine/engine.js
index 321221323c..19a0552c8c 100644
--- a/platform/javascript/js/engine/engine.js
+++ b/platform/javascript/js/engine/engine.js
@@ -1,280 +1,273 @@
+/**
+ * Projects exported for the Web expose the :js:class:`Engine` class to the JavaScript environment, that allows
+ * fine control over the engine's start-up process.
+ *
+ * This API is built in an asynchronous manner and requires basic understanding
+ * of `Promises <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Using_promises>`__.
+ *
+ * @module Engine
+ * @header HTML5 shell class reference
+ */
 const Engine = (function () {
 	const preloader = new Preloader();
 
-	let wasmExt = '.wasm';
-	let unloadAfterInit = true;
-	let loadPath = '';
 	let loadPromise = null;
+	let loadPath = '';
 	let initPromise = null;
-	let stderr = null;
-	let stdout = null;
-	let progressFunc = null;
 
-	function load(basePath) {
+	/**
+	 * @classdesc The ``Engine`` class provides methods for loading and starting exported projects on the Web. For default export
+	 * settings, this is already part of the exported HTML page. To understand practical use of the ``Engine`` class,
+	 * see :ref:`Custom HTML page for Web export <doc_customizing_html5_shell>`.
+	 *
+	 * @description Create a new Engine instance with the given configuration.
+	 *
+	 * @global
+	 * @constructor
+	 * @param {EngineConfig} initConfig The initial config for this instance.
+	 */
+	function Engine(initConfig) { // eslint-disable-line no-shadow
+		this.config = new InternalConfig(initConfig);
+		this.rtenv = null;
+	}
+
+	/**
+	 * Load the engine from the specified base path.
+	 *
+	 * @param {string} basePath Base path of the engine to load.
+	 * @param {number=} [size=0] The file size if known.
+	 * @returns {Promise} A Promise that resolves once the engine is loaded.
+	 *
+	 * @function Engine.load
+	 */
+	Engine.load = function (basePath, size) {
 		if (loadPromise == null) {
 			loadPath = basePath;
-			loadPromise = preloader.loadPromise(basePath + wasmExt);
-			preloader.setProgressFunc(progressFunc);
+			loadPromise = preloader.loadPromise(`${loadPath}.wasm`, size, true);
 			requestAnimationFrame(preloader.animateProgress);
 		}
 		return loadPromise;
-	}
+	};
 
-	function unload() {
+	/**
+	 * Unload the engine to free memory.
+	 *
+	 * This method will be called automatically depending on the configuration. See :js:attr:`unloadAfterInit`.
+	 *
+	 * @function Engine.unload
+	 */
+	Engine.unload = function () {
 		loadPromise = null;
-	}
-
-	/** @constructor */
-	function Engine() { // eslint-disable-line no-shadow
-		this.canvas = null;
-		this.executableName = '';
-		this.rtenv = null;
-		this.customLocale = null;
-		this.resizeCanvasOnStart = false;
-		this.onExecute = null;
-		this.onExit = null;
-		this.persistentPaths = ['/userfs'];
-		this.gdnativeLibs = [];
-	}
-
-	Engine.prototype.init = /** @param {string=} basePath */ function (basePath) {
-		if (initPromise) {
-			return initPromise;
-		}
-		if (loadPromise == null) {
-			if (!basePath) {
-				initPromise = Promise.reject(new Error('A base path must be provided when calling `init` and the engine is not loaded.'));
-				return initPromise;
-			}
-			load(basePath);
-		}
-		let config = {};
-		if (typeof stdout === 'function') {
-			config.print = stdout;
-		}
-		if (typeof stderr === 'function') {
-			config.printErr = stderr;
-		}
-		const me = this;
-		initPromise = new Promise(function (resolve, reject) {
-			config['locateFile'] = Utils.createLocateRewrite(loadPath);
-			config['instantiateWasm'] = Utils.createInstantiatePromise(loadPromise);
-			// Emscripten configuration.
-			config['thisProgram'] = me.executableName;
-			config['noExitRuntime'] = true;
-			config['dynamicLibraries'] = [`${me.executableName}.side.wasm`].concat(me.gdnativeLibs);
-			Godot(config).then(function (module) {
-				module['initFS'](me.persistentPaths).then(function (fs_err) {
-					me.rtenv = module;
-					if (unloadAfterInit) {
-						unload();
-					}
-					resolve();
-					config = null;
-				});
-			});
-		});
-		return initPromise;
 	};
 
-	/** @type {function(string, string):Object} */
-	Engine.prototype.preloadFile = function (file, path) {
-		return preloader.preload(file, path);
+	/**
+	 * Check whether WebGL is available. Optionally, specify a particular version of WebGL to check for.
+	 *
+	 * @param {number=} [majorVersion=1] The major WebGL version to check for.
+	 * @returns {boolean} If the given major version of WebGL is available.
+	 * @function Engine.isWebGLAvailable
+	 */
+	Engine.isWebGLAvailable = function (majorVersion = 1) {
+		try {
+			return !!document.createElement('canvas').getContext(['webgl', 'webgl2'][majorVersion - 1]);
+		} catch (e) { /* Not available */ }
+		return false;
 	};
 
-	/** @type {function(...string):Object} */
-	Engine.prototype.start = function () {
-		// Start from arguments.
-		const args = [];
-		for (let i = 0; i < arguments.length; i++) {
-			args.push(arguments[i]);
-		}
-		const me = this;
-		return me.init().then(function () {
-			if (!me.rtenv) {
-				return Promise.reject(new Error('The engine must be initialized before it can be started'));
-			}
-
-			if (!(me.canvas instanceof HTMLCanvasElement)) {
-				me.canvas = Utils.findCanvas();
-				if (!me.canvas) {
-					return Promise.reject(new Error('No canvas found in page'));
+	/**
+	 * Safe Engine constructor, creates a new prototype for every new instance to avoid prototype pollution.
+	 * @ignore
+	 * @constructor
+	 */
+	function SafeEngine(initConfig) {
+		const proto = /** @lends Engine.prototype */ {
+			/**
+			 * Initialize the engine instance. Optionally, pass the base path to the engine to load it,
+			 * if it hasn't been loaded yet. See :js:meth:`Engine.load`.
+			 *
+			 * @param {string=} basePath Base path of the engine to load.
+			 * @return {Promise} A ``Promise`` that resolves once the engine is loaded and initialized.
+			 */
+			init: function (basePath) {
+				if (initPromise) {
+					return initPromise;
+				}
+				if (loadPromise == null) {
+					if (!basePath) {
+						initPromise = Promise.reject(new Error('A base path must be provided when calling `init` and the engine is not loaded.'));
+						return initPromise;
+					}
+					Engine.load(basePath, this.config.fileSizes[`${basePath}.wasm`]);
+				}
+				const me = this;
+				function doInit(promise) {
+					return promise.then(function (response) {
+						return Godot(me.config.getModuleConfig(loadPath, response.clone()));
+					}).then(function (module) {
+						const paths = me.config.persistentPaths;
+						return module['initFS'](paths).then(function (err) {
+							return Promise.resolve(module);
+						});
+					}).then(function (module) {
+						me.rtenv = module;
+						if (me.config.unloadAfterInit) {
+							Engine.unload();
+						}
+						return Promise.resolve();
+					});
 				}
-			}
+				preloader.setProgressFunc(this.config.onProgress);
+				initPromise = doInit(loadPromise);
+				return initPromise;
+			},
 
-			// Canvas can grab focus on click, or key events won't work.
-			if (me.canvas.tabIndex < 0) {
-				me.canvas.tabIndex = 0;
-			}
+			/**
+			 * Load a file so it is available in the instance's file system once it runs. Must be called **before** starting the
+			 * instance.
+			 *
+			 * If not provided, the ``path`` is derived from the URL of the loaded file.
+			 *
+			 * @param {string|ArrayBuffer} file The file to preload.
+			 *
+			 * If a ``string`` the file will be loaded from that path.
+			 *
+			 * If an ``ArrayBuffer`` or a view on one, the buffer will used as the content of the file.
+			 *
+			 * @param {string=} path Path by which the file will be accessible. Required, if ``file`` is not a string.
+			 *
+			 * @returns {Promise} A Promise that resolves once the file is loaded.
+			 */
+			preloadFile: function (file, path) {
+				return preloader.preload(file, path, this.config.fileSizes[file]);
+			},
 
-			// Browser locale, or custom one if defined.
-			let locale = me.customLocale;
-			if (!locale) {
-				locale = navigator.languages ? navigator.languages[0] : navigator.language;
-				locale = locale.split('.')[0];
-			}
-			// Godot configuration.
-			me.rtenv['initConfig']({
-				'resizeCanvasOnStart': me.resizeCanvasOnStart,
-				'canvas': me.canvas,
-				'locale': locale,
-				'onExecute': function (p_args) {
-					if (me.onExecute) {
-						me.onExecute(p_args);
-						return 0;
+			/**
+			 * Start the engine instance using the given override configuration (if any).
+			 * :js:meth:`startGame <Engine.prototype.startGame>` can be used in typical cases instead.
+			 *
+			 * This will initialize the instance if it is not initialized. For manual initialization, see :js:meth:`init <Engine.prototype.init>`.
+			 * The engine must be loaded beforehand.
+			 *
+			 * Fails if a canvas cannot be found on the page, or not specified in the configuration.
+			 *
+			 * @param {EngineConfig} override An optional configuration override.
+			 * @return {Promise} Promise that resolves once the engine started.
+			 */
+			start: function (override) {
+				this.config.update(override);
+				const me = this;
+				return me.init().then(function () {
+					if (!me.rtenv) {
+						return Promise.reject(new Error('The engine must be initialized before it can be started'));
 					}
-					return 1;
-				},
-				'onExit': function (p_code) {
-					me.rtenv['deinitFS']();
-					if (me.onExit) {
-						me.onExit(p_code);
+
+					let config = {};
+					try {
+						config = me.config.getGodotConfig(function () {
+							me.rtenv = null;
+						});
+					} catch (e) {
+						return Promise.reject(e);
 					}
-					me.rtenv = null;
-				},
-			});
+					// Godot configuration.
+					me.rtenv['initConfig'](config);
 
-			return new Promise(function (resolve, reject) {
-				preloader.preloadedFiles.forEach(function (file) {
-					me.rtenv['copyToFS'](file.path, file.buffer);
+					// Preload GDNative libraries.
+					const libs = [];
+					me.config.gdnativeLibs.forEach(function (lib) {
+						libs.push(me.rtenv['loadDynamicLibrary'](lib, { 'loadAsync': true }));
+					});
+					return Promise.all(libs).then(function () {
+						return new Promise(function (resolve, reject) {
+							preloader.preloadedFiles.forEach(function (file) {
+								me.rtenv['copyToFS'](file.path, file.buffer);
+							});
+							preloader.preloadedFiles.length = 0; // Clear memory
+							me.rtenv['callMain'](me.config.args);
+							initPromise = null;
+							resolve();
+						});
+					});
 				});
-				preloader.preloadedFiles.length = 0; // Clear memory
-				me.rtenv['callMain'](args);
-				initPromise = null;
-				resolve();
-			});
-		});
-	};
-
-	Engine.prototype.startGame = function (execName, mainPack, extraArgs) {
-		// Start and init with execName as loadPath if not inited.
-		this.executableName = execName;
-		const me = this;
-		return Promise.all([
-			this.init(execName),
-			this.preloadFile(mainPack, mainPack),
-		]).then(function () {
-			let args = ['--main-pack', mainPack];
-			if (extraArgs) {
-				args = args.concat(extraArgs);
-			}
-			return me.start.apply(me, args);
-		});
-	};
-
-	Engine.prototype.setWebAssemblyFilenameExtension = function (override) {
-		if (String(override).length === 0) {
-			throw new Error('Invalid WebAssembly filename extension override');
-		}
-		wasmExt = String(override);
-	};
+			},
 
-	Engine.prototype.setUnloadAfterInit = function (enabled) {
-		unloadAfterInit = enabled;
-	};
-
-	Engine.prototype.setCanvas = function (canvasElem) {
-		this.canvas = canvasElem;
-	};
-
-	Engine.prototype.setCanvasResizedOnStart = function (enabled) {
-		this.resizeCanvasOnStart = enabled;
-	};
-
-	Engine.prototype.setLocale = function (locale) {
-		this.customLocale = locale;
-	};
-
-	Engine.prototype.setExecutableName = function (newName) {
-		this.executableName = newName;
-	};
-
-	Engine.prototype.setProgressFunc = function (func) {
-		progressFunc = func;
-	};
+			/**
+			 * Start the game instance using the given configuration override (if any).
+			 *
+			 * This will initialize the instance if it is not initialized. For manual initialization, see :js:meth:`init <Engine.prototype.init>`.
+			 *
+			 * This will load the engine if it is not loaded, and preload the main pck.
+			 *
+			 * This method expects the initial config (or the override) to have both the :js:attr:`executable` and :js:attr:`mainPack`
+			 * properties set (normally done by the editor during export).
+			 *
+			 * @param {EngineConfig} override An optional configuration override.
+			 * @return {Promise} Promise that resolves once the game started.
+			 */
+			startGame: function (override) {
+				this.config.update(override);
+				// Add main-pack argument.
+				const exe = this.config.executable;
+				const pack = this.config.mainPack || `${exe}.pck`;
+				this.config.args = ['--main-pack', pack].concat(this.config.args);
+				// Start and init with execName as loadPath if not inited.
+				const me = this;
+				return Promise.all([
+					this.init(exe),
+					this.preloadFile(pack, pack),
+				]).then(function () {
+					return me.start.apply(me);
+				});
+			},
 
-	Engine.prototype.setStdoutFunc = function (func) {
-		const print = function (text) {
-			let msg = text;
-			if (arguments.length > 1) {
-				msg = Array.prototype.slice.call(arguments).join(' ');
-			}
-			func(msg);
-		};
-		if (this.rtenv) {
-			this.rtenv.print = print;
-		}
-		stdout = print;
-	};
+			/**
+			 * Create a file at the specified ``path`` with the passed as ``buffer`` in the instance's file system.
+			 *
+			 * @param {string} path The location where the file will be created.
+			 * @param {ArrayBuffer} buffer The content of the file.
+			 */
+			copyToFS: function (path, buffer) {
+				if (this.rtenv == null) {
+					throw new Error('Engine must be inited before copying files');
+				}
+				this.rtenv['copyToFS'](path, buffer);
+			},
 
-	Engine.prototype.setStderrFunc = function (func) {
-		const printErr = function (text) {
-			let msg = text;
-			if (arguments.length > 1) {
-				msg = Array.prototype.slice.call(arguments).join(' ');
-			}
-			func(msg);
+			/**
+			 * Request that the current instance quit.
+			 *
+			 * This is akin the user pressing the close button in the window manager, and will
+			 * have no effect if the engine has crashed, or is stuck in a loop.
+			 *
+			 */
+			requestQuit: function () {
+				if (this.rtenv) {
+					this.rtenv['request_quit']();
+				}
+			},
 		};
-		if (this.rtenv) {
-			this.rtenv.printErr = printErr;
-		}
-		stderr = printErr;
-	};
-
-	Engine.prototype.setOnExecute = function (onExecute) {
-		this.onExecute = onExecute;
-	};
-
-	Engine.prototype.setOnExit = function (onExit) {
-		this.onExit = onExit;
-	};
-
-	Engine.prototype.copyToFS = function (path, buffer) {
-		if (this.rtenv == null) {
-			throw new Error('Engine must be inited before copying files');
-		}
-		this.rtenv['copyToFS'](path, buffer);
-	};
-
-	Engine.prototype.setPersistentPaths = function (persistentPaths) {
-		this.persistentPaths = persistentPaths;
-	};
 
-	Engine.prototype.setGDNativeLibraries = function (gdnativeLibs) {
-		this.gdnativeLibs = gdnativeLibs;
-	};
+		Engine.prototype = proto;
+		// Closure compiler exported instance methods.
+		Engine.prototype['init'] = Engine.prototype.init;
+		Engine.prototype['preloadFile'] = Engine.prototype.preloadFile;
+		Engine.prototype['start'] = Engine.prototype.start;
+		Engine.prototype['startGame'] = Engine.prototype.startGame;
+		Engine.prototype['copyToFS'] = Engine.prototype.copyToFS;
+		Engine.prototype['requestQuit'] = Engine.prototype.requestQuit;
+		// Also expose static methods as instance methods
+		Engine.prototype['load'] = Engine.load;
+		Engine.prototype['unload'] = Engine.unload;
+		Engine.prototype['isWebGLAvailable'] = Engine.isWebGLAvailable;
+		return new Engine(initConfig);
+	}
 
-	Engine.prototype.requestQuit = function () {
-		if (this.rtenv) {
-			this.rtenv['request_quit']();
-		}
-	};
+	// Closure compiler exported static methods.
+	SafeEngine['load'] = Engine.load;
+	SafeEngine['unload'] = Engine.unload;
+	SafeEngine['isWebGLAvailable'] = Engine.isWebGLAvailable;
 
-	// Closure compiler exported engine methods.
-	/** @export */
-	Engine['isWebGLAvailable'] = Utils.isWebGLAvailable;
-	Engine['load'] = load;
-	Engine['unload'] = unload;
-	Engine.prototype['init'] = Engine.prototype.init;
-	Engine.prototype['preloadFile'] = Engine.prototype.preloadFile;
-	Engine.prototype['start'] = Engine.prototype.start;
-	Engine.prototype['startGame'] = Engine.prototype.startGame;
-	Engine.prototype['setWebAssemblyFilenameExtension'] = Engine.prototype.setWebAssemblyFilenameExtension;
-	Engine.prototype['setUnloadAfterInit'] = Engine.prototype.setUnloadAfterInit;
-	Engine.prototype['setCanvas'] = Engine.prototype.setCanvas;
-	Engine.prototype['setCanvasResizedOnStart'] = Engine.prototype.setCanvasResizedOnStart;
-	Engine.prototype['setLocale'] = Engine.prototype.setLocale;
-	Engine.prototype['setExecutableName'] = Engine.prototype.setExecutableName;
-	Engine.prototype['setProgressFunc'] = Engine.prototype.setProgressFunc;
-	Engine.prototype['setStdoutFunc'] = Engine.prototype.setStdoutFunc;
-	Engine.prototype['setStderrFunc'] = Engine.prototype.setStderrFunc;
-	Engine.prototype['setOnExecute'] = Engine.prototype.setOnExecute;
-	Engine.prototype['setOnExit'] = Engine.prototype.setOnExit;
-	Engine.prototype['copyToFS'] = Engine.prototype.copyToFS;
-	Engine.prototype['setPersistentPaths'] = Engine.prototype.setPersistentPaths;
-	Engine.prototype['setGDNativeLibraries'] = Engine.prototype.setGDNativeLibraries;
-	Engine.prototype['requestQuit'] = Engine.prototype.requestQuit;
-	return Engine;
+	return SafeEngine;
 }());
 if (typeof window !== 'undefined') {
 	window['Engine'] = Engine;
diff --git a/platform/javascript/js/engine/preloader.js b/platform/javascript/js/engine/preloader.js
index ec34fb93f2..3535fdb361 100644
--- a/platform/javascript/js/engine/preloader.js
+++ b/platform/javascript/js/engine/preloader.js
@@ -1,54 +1,79 @@
 const Preloader = /** @constructor */ function () { // eslint-disable-line no-unused-vars
-	const loadXHR = function (resolve, reject, file, tracker, attempts) {
-		const xhr = new XMLHttpRequest();
+	function getTrackedResponse(response, load_status) {
+		let clen = 0;
+		let compressed = false;
+		response.headers.forEach(function (value, header) {
+			const h = header.toLowerCase().trim();
+			// We can't accurately compute compressed stream length.
+			if (h === 'content-encoding') {
+				compressed = true;
+			} else if (h === 'content-length') {
+				const length = parseInt(value, 10);
+				if (!Number.isNaN(length) && length > 0) {
+					clen = length;
+				}
+			}
+		});
+		if (!compressed && clen) {
+			load_status.total = clen;
+		}
+		function onloadprogress(reader, controller) {
+			return reader.read().then(function (result) {
+				if (load_status.done) {
+					return Promise.resolve();
+				}
+				if (result.value) {
+					controller.enqueue(result.value);
+					load_status.loaded += result.value.length;
+				}
+				if (!result.done) {
+					return onloadprogress(reader, controller);
+				}
+				load_status.done = true;
+				return Promise.resolve();
+			});
+		}
+		const reader = response.body.getReader();
+		return new Response(new ReadableStream({
+			start: function (controller) {
+				onloadprogress(reader, controller).then(function () {
+					controller.close();
+				});
+			},
+		}), { headers: response.headers });
+	}
+
+	function loadFetch(file, tracker, fileSize, raw) {
 		tracker[file] = {
-			total: 0,
+			total: fileSize || 0,
 			loaded: 0,
-			final: false,
+			done: false,
 		};
-		xhr.onerror = function () {
+		return fetch(file).then(function (response) {
+			if (!response.ok) {
+				return Promise.reject(new Error(`Failed loading file '${file}'`));
+			}
+			const tr = getTrackedResponse(response, tracker[file]);
+			if (raw) {
+				return Promise.resolve(tr);
+			}
+			return tr.arrayBuffer();
+		});
+	}
+
+	function retry(func, attempts = 1) {
+		function onerror(err) {
 			if (attempts <= 1) {
-				reject(new Error(`Failed loading file '${file}'`));
-			} else {
+				return Promise.reject(err);
+			}
+			return new Promise(function (resolve, reject) {
 				setTimeout(function () {
-					loadXHR(resolve, reject, file, tracker, attempts - 1);
+					retry(func, attempts - 1).then(resolve).catch(reject);
 				}, 1000);
-			}
-		};
-		xhr.onabort = function () {
-			tracker[file].final = true;
-			reject(new Error(`Loading file '${file}' was aborted.`));
-		};
-		xhr.onloadstart = function (ev) {
-			tracker[file].total = ev.total;
-			tracker[file].loaded = ev.loaded;
-		};
-		xhr.onprogress = function (ev) {
-			tracker[file].loaded = ev.loaded;
-			tracker[file].total = ev.total;
-		};
-		xhr.onload = function () {
-			if (xhr.status >= 400) {
-				if (xhr.status < 500 || attempts <= 1) {
-					reject(new Error(`Failed loading file '${file}': ${xhr.statusText}`));
-					xhr.abort();
-				} else {
-					setTimeout(function () {
-						loadXHR(resolve, reject, file, tracker, attempts - 1);
-					}, 1000);
-				}
-			} else {
-				tracker[file].final = true;
-				resolve(xhr);
-			}
-		};
-		// Make request.
-		xhr.open('GET', file);
-		if (!file.endsWith('.js')) {
-			xhr.responseType = 'arraybuffer';
+			});
 		}
-		xhr.send();
-	};
+		return func().catch(onerror);
+	}
 
 	const DOWNLOAD_ATTEMPTS_MAX = 4;
 	const loadingFiles = {};
@@ -63,7 +88,7 @@ const Preloader = /** @constructor */ function () { // eslint-disable-line no-un
 
 		Object.keys(loadingFiles).forEach(function (file) {
 			const stat = loadingFiles[file];
-			if (!stat.final) {
+			if (!stat.done) {
 				progressIsFinal = false;
 			}
 			if (!totalIsValid || stat.total === 0) {
@@ -92,21 +117,19 @@ const Preloader = /** @constructor */ function () { // eslint-disable-line no-un
 		progressFunc = callback;
 	};
 
-	this.loadPromise = function (file) {
-		return new Promise(function (resolve, reject) {
-			loadXHR(resolve, reject, file, loadingFiles, DOWNLOAD_ATTEMPTS_MAX);
-		});
+	this.loadPromise = function (file, fileSize, raw = false) {
+		return retry(loadFetch.bind(null, file, loadingFiles, fileSize, raw), DOWNLOAD_ATTEMPTS_MAX);
 	};
 
 	this.preloadedFiles = [];
-	this.preload = function (pathOrBuffer, destPath) {
+	this.preload = function (pathOrBuffer, destPath, fileSize) {
 		let buffer = null;
 		if (typeof pathOrBuffer === 'string') {
 			const me = this;
-			return this.loadPromise(pathOrBuffer).then(function (xhr) {
+			return this.loadPromise(pathOrBuffer, fileSize).then(function (buf) {
 				me.preloadedFiles.push({
 					path: destPath || pathOrBuffer,
-					buffer: xhr.response,
+					buffer: buf,
 				});
 				return Promise.resolve();
 			});
diff --git a/platform/javascript/js/engine/utils.js b/platform/javascript/js/engine/utils.js
deleted file mode 100644
index 9273bbad42..0000000000
--- a/platform/javascript/js/engine/utils.js
+++ /dev/null
@@ -1,58 +0,0 @@
-const Utils = { // eslint-disable-line no-unused-vars
-
-	createLocateRewrite: function (execName) {
-		function rw(path) {
-			if (path.endsWith('.worker.js')) {
-				return `${execName}.worker.js`;
-			} else if (path.endsWith('.audio.worklet.js')) {
-				return `${execName}.audio.worklet.js`;
-			} else if (path.endsWith('.js')) {
-				return `${execName}.js`;
-			} else if (path.endsWith('.side.wasm')) {
-				return `${execName}.side.wasm`;
-			} else if (path.endsWith('.wasm')) {
-				return `${execName}.wasm`;
-			}
-			return path;
-		}
-		return rw;
-	},
-
-	createInstantiatePromise: function (wasmLoader) {
-		let loader = wasmLoader;
-		function instantiateWasm(imports, onSuccess) {
-			loader.then(function (xhr) {
-				WebAssembly.instantiate(xhr.response, imports).then(function (result) {
-					onSuccess(result['instance'], result['module']);
-				});
-			});
-			loader = null;
-			return {};
-		}
-
-		return instantiateWasm;
-	},
-
-	findCanvas: function () {
-		const nodes = document.getElementsByTagName('canvas');
-		if (nodes.length && nodes[0] instanceof HTMLCanvasElement) {
-			return nodes[0];
-		}
-		return null;
-	},
-
-	isWebGLAvailable: function (majorVersion = 1) {
-		let testContext = false;
-		try {
-			const 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) {
-			// Not available
-		}
-		return !!testContext;
-	},
-};
diff --git a/platform/javascript/js/jsdoc2rst/publish.js b/platform/javascript/js/jsdoc2rst/publish.js
new file mode 100644
index 0000000000..ad9c0fbaaa
--- /dev/null
+++ b/platform/javascript/js/jsdoc2rst/publish.js
@@ -0,0 +1,354 @@
+/* eslint-disable strict */
+
+'use strict';
+
+const fs = require('fs');
+
+class JSDoclet {
+	constructor(doc) {
+		this.doc = doc;
+		this.description = doc['description'] || '';
+		this.name = doc['name'] || 'unknown';
+		this.longname = doc['longname'] || '';
+		this.types = [];
+		if (doc['type'] && doc['type']['names']) {
+			this.types = doc['type']['names'].slice();
+		}
+		this.type = this.types.length > 0 ? this.types.join('\\|') : '*';
+		this.variable = doc['variable'] || false;
+		this.kind = doc['kind'] || '';
+		this.memberof = doc['memberof'] || null;
+		this.scope = doc['scope'] || '';
+		this.members = [];
+		this.optional = doc['optional'] || false;
+		this.defaultvalue = doc['defaultvalue'];
+		this.summary = doc['summary'] || null;
+		this.classdesc = doc['classdesc'] || null;
+
+		// Parameters (functions)
+		this.params = [];
+		this.returns = doc['returns'] ? doc['returns'][0]['type']['names'][0] : 'void';
+		this.returns_desc = doc['returns'] ? doc['returns'][0]['description'] : null;
+
+		this.params = (doc['params'] || []).slice().map((p) => new JSDoclet(p));
+
+		// Custom tags
+		this.tags = doc['tags'] || [];
+		this.header = this.tags.filter((t) => t['title'] === 'header').map((t) => t['text']).pop() || null;
+	}
+
+	add_member(obj) {
+		this.members.push(obj);
+	}
+
+	is_static() {
+		return this.scope === 'static';
+	}
+
+	is_instance() {
+		return this.scope === 'instance';
+	}
+
+	is_object() {
+		return this.kind === 'Object' || (this.kind === 'typedef' && this.type === 'Object');
+	}
+
+	is_class() {
+		return this.kind === 'class';
+	}
+
+	is_function() {
+		return this.kind === 'function' || (this.kind === 'typedef' && this.type === 'function');
+	}
+
+	is_module() {
+		return this.kind === 'module';
+	}
+}
+
+function format_table(f, data, depth = 0) {
+	if (!data.length) {
+		return;
+	}
+
+	const column_sizes = new Array(data[0].length).fill(0);
+
+	data.forEach((row) => {
+		row.forEach((e, idx) => {
+			column_sizes[idx] = Math.max(e.length, column_sizes[idx]);
+		});
+	});
+
+	const indent = ' '.repeat(depth);
+	let sep = indent;
+	column_sizes.forEach((size) => {
+		sep += '+';
+		sep += '-'.repeat(size + 2);
+	});
+	sep += '+\n';
+	f.write(sep);
+
+	data.forEach((row) => {
+		let row_text = `${indent}|`;
+		row.forEach((entry, idx) => {
+			row_text += ` ${entry.padEnd(column_sizes[idx])} |`;
+		});
+		row_text += '\n';
+		f.write(row_text);
+		f.write(sep);
+	});
+
+	f.write('\n');
+}
+
+function make_header(header, sep) {
+	return `${header}\n${sep.repeat(header.length)}\n\n`;
+}
+
+function indent_multiline(text, depth) {
+	const indent = ' '.repeat(depth);
+	return text.split('\n').map((l) => (l === '' ? l : indent + l)).join('\n');
+}
+
+function make_rst_signature(obj, types = false, style = false) {
+	let out = '';
+	const fmt = style ? '*' : '';
+	obj.params.forEach((arg, idx) => {
+		if (idx > 0) {
+			if (arg.optional) {
+				out += ` ${fmt}[`;
+			}
+			out += ', ';
+		} else {
+			out += ' ';
+			if (arg.optional) {
+				out += `${fmt}[ `;
+			}
+		}
+		if (types) {
+			out += `${arg.type} `;
+		}
+		const variable = arg.variable ? '...' : '';
+		const defval = arg.defaultvalue !== undefined ? `=${arg.defaultvalue}` : '';
+		out += `${variable}${arg.name}${defval}`;
+		if (arg.optional) {
+			out += ` ]${fmt}`;
+		}
+	});
+	out += ' ';
+	return out;
+}
+
+function make_rst_param(f, obj, depth = 0) {
+	const indent = ' '.repeat(depth * 3);
+	f.write(indent);
+	f.write(`:param ${obj.type} ${obj.name}:\n`);
+	f.write(indent_multiline(obj.description, (depth + 1) * 3));
+	f.write('\n\n');
+}
+
+function make_rst_attribute(f, obj, depth = 0, brief = false) {
+	const indent = ' '.repeat(depth * 3);
+	f.write(indent);
+	f.write(`.. js:attribute:: ${obj.name}\n\n`);
+
+	if (brief) {
+		if (obj.summary) {
+			f.write(indent_multiline(obj.summary, (depth + 1) * 3));
+		}
+		f.write('\n\n');
+		return;
+	}
+
+	f.write(indent_multiline(obj.description, (depth + 1) * 3));
+	f.write('\n\n');
+
+	f.write(indent);
+	f.write(`   :type: ${obj.type}\n\n`);
+
+	if (obj.defaultvalue !== undefined) {
+		let defval = obj.defaultvalue;
+		if (defval === '') {
+			defval = '""';
+		}
+		f.write(indent);
+		f.write(`   :value: \`\`${defval}\`\`\n\n`);
+	}
+}
+
+function make_rst_function(f, obj, depth = 0) {
+	let prefix = '';
+	if (obj.is_instance()) {
+		prefix = 'prototype.';
+	}
+
+	const indent = ' '.repeat(depth * 3);
+	const sig = make_rst_signature(obj);
+	f.write(indent);
+	f.write(`.. js:function:: ${prefix}${obj.name}(${sig})\n`);
+	f.write('\n');
+
+	f.write(indent_multiline(obj.description, (depth + 1) * 3));
+	f.write('\n\n');
+
+	obj.params.forEach((param) => {
+		make_rst_param(f, param, depth + 1);
+	});
+
+	if (obj.returns !== 'void') {
+		f.write(indent);
+		f.write('   :return:\n');
+		f.write(indent_multiline(obj.returns_desc, (depth + 2) * 3));
+		f.write('\n\n');
+		f.write(indent);
+		f.write(`   :rtype: ${obj.returns}\n\n`);
+	}
+}
+
+function make_rst_object(f, obj) {
+	let brief = false;
+	// Our custom header flag.
+	if (obj.header !== null) {
+		f.write(make_header(obj.header, '-'));
+		f.write(`${obj.description}\n\n`);
+		brief = true;
+	}
+
+	// Format members table and descriptions
+	const data = [['type', 'name']].concat(obj.members.map((m) => [m.type, `:js:attr:\`${m.name}\``]));
+
+	f.write(make_header('Properties', '^'));
+	format_table(f, data, 0);
+
+	make_rst_attribute(f, obj, 0, brief);
+
+	if (!obj.members.length) {
+		return;
+	}
+
+	f.write('   **Property Descriptions**\n\n');
+
+	// Properties first
+	obj.members.filter((m) => !m.is_function()).forEach((m) => {
+		make_rst_attribute(f, m, 1);
+	});
+
+	// Callbacks last
+	obj.members.filter((m) => m.is_function()).forEach((m) => {
+		make_rst_function(f, m, 1);
+	});
+}
+
+function make_rst_class(f, obj) {
+	const header = obj.header ? obj.header : obj.name;
+	f.write(make_header(header, '-'));
+
+	if (obj.classdesc) {
+		f.write(`${obj.classdesc}\n\n`);
+	}
+
+	const funcs = obj.members.filter((m) => m.is_function());
+	function make_data(m) {
+		const base = m.is_static() ? obj.name : `${obj.name}.prototype`;
+		const params = make_rst_signature(m, true, true);
+		const sig = `:js:attr:\`${m.name} <${base}.${m.name}>\` **(**${params}**)**`;
+		return [m.returns, sig];
+	}
+	const sfuncs = funcs.filter((m) => m.is_static());
+	const ifuncs = funcs.filter((m) => !m.is_static());
+
+	f.write(make_header('Static Methods', '^'));
+	format_table(f, sfuncs.map((m) => make_data(m)));
+
+	f.write(make_header('Instance Methods', '^'));
+	format_table(f, ifuncs.map((m) => make_data(m)));
+
+	const sig = make_rst_signature(obj);
+	f.write(`.. js:class:: ${obj.name}(${sig})\n\n`);
+	f.write(indent_multiline(obj.description, 3));
+	f.write('\n\n');
+
+	obj.params.forEach((p) => {
+		make_rst_param(f, p, 1);
+	});
+
+	f.write('   **Static Methods**\n\n');
+	sfuncs.forEach((m) => {
+		make_rst_function(f, m, 1);
+	});
+
+	f.write('   **Instance Methods**\n\n');
+	ifuncs.forEach((m) => {
+		make_rst_function(f, m, 1);
+	});
+}
+
+function make_rst_module(f, obj) {
+	const header = obj.header !== null ? obj.header : obj.name;
+	f.write(make_header(header, '='));
+	f.write(obj.description);
+	f.write('\n\n');
+}
+
+function write_base_object(f, obj) {
+	if (obj.is_object()) {
+		make_rst_object(f, obj);
+	} else if (obj.is_function()) {
+		make_rst_function(f, obj);
+	} else if (obj.is_class()) {
+		make_rst_class(f, obj);
+	} else if (obj.is_module()) {
+		make_rst_module(f, obj);
+	}
+}
+
+function generate(f, docs) {
+	const globs = [];
+	const SYMBOLS = {};
+	docs.filter((d) => !d.ignore && d.kind !== 'package').forEach((d) => {
+		SYMBOLS[d.name] = d;
+		if (d.memberof) {
+			const up = SYMBOLS[d.memberof];
+			if (up === undefined) {
+				console.log(d); // eslint-disable-line no-console
+				console.log(`Undefined symbol! ${d.memberof}`); // eslint-disable-line no-console
+				throw new Error('Undefined symbol!');
+			}
+			SYMBOLS[d.memberof].add_member(d);
+		} else {
+			globs.push(d);
+		}
+	});
+
+	f.write('.. _doc_html5_shell_classref:\n\n');
+	globs.forEach((obj) => write_base_object(f, obj));
+}
+
+/**
+ * Generate documentation output.
+ *
+ * @param {TAFFY} data - A TaffyDB collection representing
+ *                       all the symbols documented in your code.
+ * @param {object} opts - An object with options information.
+ */
+exports.publish = function (data, opts) {
+	const docs = data().get().filter((doc) => !doc.undocumented && !doc.ignore).map((doc) => new JSDoclet(doc));
+	const dest = opts.destination;
+	if (dest === 'dry-run') {
+		process.stdout.write('Dry run... ');
+		generate({
+			write: function () { /* noop */ },
+		}, docs);
+		process.stdout.write('Okay!\n');
+		return;
+	}
+	if (dest !== '' && !dest.endsWith('.rst')) {
+		throw new Error('Destination file must be either a ".rst" file, or an empty string (for printing to stdout)');
+	}
+	if (dest !== '') {
+		const f = fs.createWriteStream(dest);
+		generate(f, docs);
+	} else {
+		generate(process.stdout, docs);
+	}
+};
diff --git a/platform/javascript/js/libs/library_godot_audio.js b/platform/javascript/js/libs/library_godot_audio.js
index 8e385e9176..ac4055516c 100644
--- a/platform/javascript/js/libs/library_godot_audio.js
+++ b/platform/javascript/js/libs/library_godot_audio.js
@@ -238,6 +238,9 @@ const GodotAudioWorklet = {
 
 		close: function () {
 			return new Promise(function (resolve, reject) {
+				if (GodotAudioWorklet.promise === null) {
+					return;
+				}
 				GodotAudioWorklet.promise.then(function () {
 					GodotAudioWorklet.worklet.port.postMessage({
 						'cmd': 'stop',
@@ -247,7 +250,7 @@ const GodotAudioWorklet = {
 					GodotAudioWorklet.worklet = null;
 					GodotAudioWorklet.promise = null;
 					resolve();
-				});
+				}).catch(function (err) { /* aborted? */ });
 			});
 		},
 	},
diff --git a/platform/javascript/js/libs/library_godot_display.js b/platform/javascript/js/libs/library_godot_display.js
index 9ec295b39f..99aa4793d9 100644
--- a/platform/javascript/js/libs/library_godot_display.js
+++ b/platform/javascript/js/libs/library_godot_display.js
@@ -192,33 +192,45 @@ const GodotDisplayDragDrop = {
 				GodotDisplayDragDrop.promises = [];
 				GodotDisplayDragDrop.pending_files = [];
 				callback(drops);
-				const dirs = [DROP.substr(0, DROP.length - 1)];
-				// Remove temporary files
-				files.forEach(function (file) {
-					FS.unlink(file);
-					let dir = file.replace(DROP, '');
-					let idx = dir.lastIndexOf('/');
-					while (idx > 0) {
-						dir = dir.substr(0, idx);
-						if (dirs.indexOf(DROP + dir) === -1) {
-							dirs.push(DROP + dir);
-						}
-						idx = dir.lastIndexOf('/');
-					}
-				});
-				// Remove dirs.
-				dirs.sort(function (a, b) {
-					const al = (a.match(/\//g) || []).length;
-					const bl = (b.match(/\//g) || []).length;
-					if (al > bl) {
-						return -1;
-					} else if (al < bl) {
-						return 1;
+				if (GodotConfig.persistent_drops) {
+					// Delay removal at exit.
+					GodotOS.atexit(function (resolve, reject) {
+						GodotDisplayDragDrop.remove_drop(files, DROP);
+						resolve();
+					});
+				} else {
+					GodotDisplayDragDrop.remove_drop(files, DROP);
+				}
+			});
+		},
+
+		remove_drop: function (files, drop_path) {
+			const dirs = [drop_path.substr(0, drop_path.length - 1)];
+			// Remove temporary files
+			files.forEach(function (file) {
+				FS.unlink(file);
+				let dir = file.replace(drop_path, '');
+				let idx = dir.lastIndexOf('/');
+				while (idx > 0) {
+					dir = dir.substr(0, idx);
+					if (dirs.indexOf(drop_path + dir) === -1) {
+						dirs.push(drop_path + dir);
 					}
-					return 0;
-				}).forEach(function (dir) {
-					FS.rmdir(dir);
-				});
+					idx = dir.lastIndexOf('/');
+				}
+			});
+			// Remove dirs.
+			dirs.sort(function (a, b) {
+				const al = (a.match(/\//g) || []).length;
+				const bl = (b.match(/\//g) || []).length;
+				if (al > bl) {
+					return -1;
+				} else if (al < bl) {
+					return 1;
+				}
+				return 0;
+			}).forEach(function (dir) {
+				FS.rmdir(dir);
 			});
 		},
 
@@ -231,6 +243,105 @@ const GodotDisplayDragDrop = {
 };
 mergeInto(LibraryManager.library, GodotDisplayDragDrop);
 
+const GodotDisplayVK = {
+
+	$GodotDisplayVK__deps: ['$GodotRuntime', '$GodotConfig', '$GodotDisplayListeners'],
+	$GodotDisplayVK__postset: 'GodotOS.atexit(function(resolve, reject) { GodotDisplayVK.clear(); resolve(); });',
+	$GodotDisplayVK: {
+		textinput: null,
+		textarea: null,
+
+		available: function () {
+			return GodotConfig.virtual_keyboard && 'ontouchstart' in window;
+		},
+
+		init: function (input_cb) {
+			function create(what) {
+				const elem = document.createElement(what);
+				elem.style.display = 'none';
+				elem.style.position = 'absolute';
+				elem.style.zIndex = '-1';
+				elem.style.background = 'transparent';
+				elem.style.padding = '0px';
+				elem.style.margin = '0px';
+				elem.style.overflow = 'hidden';
+				elem.style.width = '0px';
+				elem.style.height = '0px';
+				elem.style.border = '0px';
+				elem.style.outline = 'none';
+				elem.readonly = true;
+				elem.disabled = true;
+				GodotDisplayListeners.add(elem, 'input', function (evt) {
+					const c_str = GodotRuntime.allocString(elem.value);
+					input_cb(c_str, elem.selectionEnd);
+					GodotRuntime.free(c_str);
+				}, false);
+				GodotDisplayListeners.add(elem, 'blur', function (evt) {
+					elem.style.display = 'none';
+					elem.readonly = true;
+					elem.disabled = true;
+				}, false);
+				GodotConfig.canvas.insertAdjacentElement('beforebegin', elem);
+				return elem;
+			}
+			GodotDisplayVK.textinput = create('input');
+			GodotDisplayVK.textarea = create('textarea');
+			GodotDisplayVK.updateSize();
+		},
+		show: function (text, multiline, start, end) {
+			if (!GodotDisplayVK.textinput || !GodotDisplayVK.textarea) {
+				return;
+			}
+			if (GodotDisplayVK.textinput.style.display !== '' || GodotDisplayVK.textarea.style.display !== '') {
+				GodotDisplayVK.hide();
+			}
+			GodotDisplayVK.updateSize();
+			const elem = multiline ? GodotDisplayVK.textarea : GodotDisplayVK.textinput;
+			elem.readonly = false;
+			elem.disabled = false;
+			elem.value = text;
+			elem.style.display = 'block';
+			elem.focus();
+			elem.setSelectionRange(start, end);
+		},
+		hide: function () {
+			if (!GodotDisplayVK.textinput || !GodotDisplayVK.textarea) {
+				return;
+			}
+			[GodotDisplayVK.textinput, GodotDisplayVK.textarea].forEach(function (elem) {
+				elem.blur();
+				elem.style.display = 'none';
+				elem.value = '';
+			});
+		},
+		updateSize: function () {
+			if (!GodotDisplayVK.textinput || !GodotDisplayVK.textarea) {
+				return;
+			}
+			const rect = GodotConfig.canvas.getBoundingClientRect();
+			function update(elem) {
+				elem.style.left = `${rect.left}px`;
+				elem.style.top = `${rect.top}px`;
+				elem.style.width = `${rect.width}px`;
+				elem.style.height = `${rect.height}px`;
+			}
+			update(GodotDisplayVK.textinput);
+			update(GodotDisplayVK.textarea);
+		},
+		clear: function () {
+			if (GodotDisplayVK.textinput) {
+				GodotDisplayVK.textinput.remove();
+				GodotDisplayVK.textinput = null;
+			}
+			if (GodotDisplayVK.textarea) {
+				GodotDisplayVK.textarea.remove();
+				GodotDisplayVK.textarea = null;
+			}
+		},
+	},
+};
+mergeInto(LibraryManager.library, GodotDisplayVK);
+
 /*
  * Display server cursor helper.
  * Keeps track of cursor status and custom shapes.
@@ -396,13 +507,122 @@ const GodotDisplayGamepads = {
 };
 mergeInto(LibraryManager.library, GodotDisplayGamepads);
 
+const GodotDisplayScreen = {
+	$GodotDisplayScreen__deps: ['$GodotConfig', '$GodotOS', '$GL', 'emscripten_webgl_get_current_context'],
+	$GodotDisplayScreen: {
+		desired_size: [0, 0],
+		hidpi: true,
+		getPixelRatio: function () {
+			return GodotDisplayScreen.hidpi ? window.devicePixelRatio || 1 : 1;
+		},
+		isFullscreen: function () {
+			const elem = document.fullscreenElement || document.mozFullscreenElement
+				|| document.webkitFullscreenElement || document.msFullscreenElement;
+			if (elem) {
+				return elem === GodotConfig.canvas;
+			}
+			// But maybe knowing the element is not supported.
+			return document.fullscreen || document.mozFullScreen
+				|| document.webkitIsFullscreen;
+		},
+		hasFullscreen: function () {
+			return document.fullscreenEnabled || document.mozFullScreenEnabled
+				|| document.webkitFullscreenEnabled;
+		},
+		requestFullscreen: function () {
+			if (!GodotDisplayScreen.hasFullscreen()) {
+				return 1;
+			}
+			const canvas = GodotConfig.canvas;
+			try {
+				const promise = (canvas.requestFullscreen || canvas.msRequestFullscreen
+					|| canvas.mozRequestFullScreen || canvas.mozRequestFullscreen
+					|| canvas.webkitRequestFullscreen
+				).call(canvas);
+				// Some browsers (Safari) return undefined.
+				// For the standard ones, we need to catch it.
+				if (promise) {
+					promise.catch(function () {
+						// nothing to do.
+					});
+				}
+			} catch (e) {
+				return 1;
+			}
+			return 0;
+		},
+		exitFullscreen: function () {
+			if (!GodotDisplayScreen.isFullscreen()) {
+				return 0;
+			}
+			try {
+				const promise = document.exitFullscreen();
+				if (promise) {
+					promise.catch(function () {
+						// nothing to do.
+					});
+				}
+			} catch (e) {
+				return 1;
+			}
+			return 0;
+		},
+		_updateGL: function () {
+			const gl_context_handle = _emscripten_webgl_get_current_context(); // eslint-disable-line no-undef
+			const gl = GL.getContext(gl_context_handle);
+			if (gl) {
+				GL.resizeOffscreenFramebuffer(gl);
+			}
+		},
+		updateSize: function () {
+			const isFullscreen = GodotDisplayScreen.isFullscreen();
+			const wantsFullWindow = GodotConfig.canvas_resize_policy === 2;
+			const noResize = GodotConfig.canvas_resize_policy === 0;
+			const wwidth = GodotDisplayScreen.desired_size[0];
+			const wheight = GodotDisplayScreen.desired_size[1];
+			const canvas = GodotConfig.canvas;
+			let width = wwidth;
+			let height = wheight;
+			if (noResize) {
+				// Don't resize canvas, just update GL if needed.
+				if (canvas.width !== width || canvas.height !== height) {
+					GodotDisplayScreen.desired_size = [canvas.width, canvas.height];
+					GodotDisplayScreen._updateGL();
+					return 1;
+				}
+				return 0;
+			}
+			const scale = GodotDisplayScreen.getPixelRatio();
+			if (isFullscreen || wantsFullWindow) {
+				// We need to match screen size.
+				width = window.innerWidth * scale;
+				height = window.innerHeight * scale;
+			}
+			const csw = `${width / scale}px`;
+			const csh = `${height / scale}px`;
+			if (canvas.style.width !== csw || canvas.style.height !== csh || canvas.width !== width || canvas.height !== height) {
+				// Size doesn't match.
+				// Resize canvas, set correct CSS pixel size, update GL.
+				canvas.width = width;
+				canvas.height = height;
+				canvas.style.width = csw;
+				canvas.style.height = csh;
+				GodotDisplayScreen._updateGL();
+				return 1;
+			}
+			return 0;
+		},
+	},
+};
+mergeInto(LibraryManager.library, GodotDisplayScreen);
+
 /**
  * Display server interface.
  *
  * Exposes all the functions needed by DisplayServer implementation.
  */
 const GodotDisplay = {
-	$GodotDisplay__deps: ['$GodotConfig', '$GodotRuntime', '$GodotDisplayCursor', '$GodotDisplayListeners', '$GodotDisplayDragDrop', '$GodotDisplayGamepads'],
+	$GodotDisplay__deps: ['$GodotConfig', '$GodotRuntime', '$GodotDisplayCursor', '$GodotDisplayListeners', '$GodotDisplayDragDrop', '$GodotDisplayGamepads', '$GodotDisplayScreen', '$GodotDisplayVK'],
 	$GodotDisplay: {
 		window_icon: '',
 		findDPI: function () {
@@ -450,7 +670,53 @@ const GodotDisplay = {
 
 	godot_js_display_pixel_ratio_get__sig: 'f',
 	godot_js_display_pixel_ratio_get: function () {
-		return window.devicePixelRatio || 1;
+		return GodotDisplayScreen.getPixelRatio();
+	},
+
+	godot_js_display_fullscreen_request__sig: 'i',
+	godot_js_display_fullscreen_request: function () {
+		return GodotDisplayScreen.requestFullscreen();
+	},
+
+	godot_js_display_fullscreen_exit__sig: 'i',
+	godot_js_display_fullscreen_exit: function () {
+		return GodotDisplayScreen.exitFullscreen();
+	},
+
+	godot_js_display_desired_size_set__sig: 'v',
+	godot_js_display_desired_size_set: function (width, height) {
+		GodotDisplayScreen.desired_size = [width, height];
+		GodotDisplayScreen.updateSize();
+	},
+
+	godot_js_display_size_update__sig: 'i',
+	godot_js_display_size_update: function () {
+		const updated = GodotDisplayScreen.updateSize();
+		if (updated) {
+			GodotDisplayVK.updateSize();
+		}
+		return updated;
+	},
+
+	godot_js_display_screen_size_get__sig: 'vii',
+	godot_js_display_screen_size_get: function (width, height) {
+		const scale = GodotDisplayScreen.getPixelRatio();
+		GodotRuntime.setHeapValue(width, window.screen.width * scale, 'i32');
+		GodotRuntime.setHeapValue(height, window.screen.height * scale, 'i32');
+	},
+
+	godot_js_display_window_size_get: function (p_width, p_height) {
+		GodotRuntime.setHeapValue(p_width, GodotConfig.canvas.width, 'i32');
+		GodotRuntime.setHeapValue(p_height, GodotConfig.canvas.height, 'i32');
+	},
+
+	godot_js_display_compute_position: function (x, y, r_x, r_y) {
+		const canvas = GodotConfig.canvas;
+		const rect = canvas.getBoundingClientRect();
+		const rw = canvas.width / rect.width;
+		const rh = canvas.height / rect.height;
+		GodotRuntime.setHeapValue(r_x, (x - rect.x) * rw, 'i32');
+		GodotRuntime.setHeapValue(r_y, (y - rect.y) * rh, 'i32');
 	},
 
 	/*
@@ -466,13 +732,6 @@ const GodotDisplay = {
 		return document.activeElement === GodotConfig.canvas;
 	},
 
-	godot_js_display_canvas_bounding_rect_position_get__sig: 'vii',
-	godot_js_display_canvas_bounding_rect_position_get: function (r_x, r_y) {
-		const brect = GodotConfig.canvas.getBoundingClientRect();
-		GodotRuntime.setHeapValue(r_x, brect.x, 'i32');
-		GodotRuntime.setHeapValue(r_y, brect.y, 'i32');
-	},
-
 	/*
 	 * Touchscreen
 	 */
@@ -516,15 +775,6 @@ const GodotDisplay = {
 	/*
 	 * Window
 	 */
-	godot_js_display_window_request_fullscreen__sig: 'v',
-	godot_js_display_window_request_fullscreen: function () {
-		const canvas = GodotConfig.canvas;
-		(canvas.requestFullscreen || canvas.msRequestFullscreen
-			|| canvas.mozRequestFullScreen || canvas.mozRequestFullscreen
-			|| canvas.webkitRequestFullscreen
-		).call(canvas);
-	},
-
 	godot_js_display_window_title_set__sig: 'vi',
 	godot_js_display_window_title_set: function (p_data) {
 		document.title = GodotRuntime.parseString(p_data);
@@ -540,7 +790,7 @@ const GodotDisplay = {
 			document.head.appendChild(link);
 		}
 		const old_icon = GodotDisplay.window_icon;
-		const png = new Blob([GodotRuntime.heapCopy(HEAPU8, p_ptr, p_len)], { type: 'image/png' });
+		const png = new Blob([GodotRuntime.heapSlice(HEAPU8, p_ptr, p_len)], { type: 'image/png' });
 		GodotDisplay.window_icon = URL.createObjectURL(png);
 		link.href = GodotDisplay.window_icon;
 		if (old_icon) {
@@ -580,7 +830,7 @@ const GodotDisplay = {
 		const shape = GodotRuntime.parseString(p_shape);
 		const old_shape = GodotDisplayCursor.cursors[shape];
 		if (p_len > 0) {
-			const png = new Blob([GodotRuntime.heapCopy(HEAPU8, p_ptr, p_len)], { type: 'image/png' });
+			const png = new Blob([GodotRuntime.heapSlice(HEAPU8, p_ptr, p_len)], { type: 'image/png' });
 			const url = URL.createObjectURL(png);
 			GodotDisplayCursor.cursors[shape] = {
 				url: url,
@@ -645,8 +895,8 @@ const GodotDisplay = {
 		GodotDisplayListeners.add(canvas, 'drop', GodotDisplayDragDrop.handler(dropFiles));
 	},
 
-	godot_js_display_setup_canvas__sig: 'v',
-	godot_js_display_setup_canvas: function () {
+	godot_js_display_setup_canvas__sig: 'viiii',
+	godot_js_display_setup_canvas: function (p_width, p_height, p_fullscreen, p_hidpi) {
 		const canvas = GodotConfig.canvas;
 		GodotDisplayListeners.add(canvas, 'contextmenu', function (ev) {
 			ev.preventDefault();
@@ -655,6 +905,54 @@ const GodotDisplay = {
 			alert('WebGL context lost, please reload the page'); // eslint-disable-line no-alert
 			ev.preventDefault();
 		}, false);
+		GodotDisplayScreen.hidpi = !!p_hidpi;
+		switch (GodotConfig.canvas_resize_policy) {
+		case 0: // None
+			GodotDisplayScreen.desired_size = [canvas.width, canvas.height];
+			break;
+		case 1: // Project
+			GodotDisplayScreen.desired_size = [p_width, p_height];
+			break;
+		default: // Full window
+			// Ensure we display in the right place, the size will be handled by updateSize
+			canvas.style.position = 'absolute';
+			canvas.style.top = 0;
+			canvas.style.left = 0;
+			break;
+		}
+		GodotDisplayScreen.updateSize();
+		if (p_fullscreen) {
+			GodotDisplayScreen.requestFullscreen();
+		}
+	},
+
+	/*
+	 * Virtual Keyboard
+	 */
+	godot_js_display_vk_show__sig: 'viiii',
+	godot_js_display_vk_show: function (p_text, p_multiline, p_start, p_end) {
+		const text = GodotRuntime.parseString(p_text);
+		const start = p_start > 0 ? p_start : 0;
+		const end = p_end > 0 ? p_end : start;
+		GodotDisplayVK.show(text, p_multiline, start, end);
+	},
+
+	godot_js_display_vk_hide__sig: 'v',
+	godot_js_display_vk_hide: function () {
+		GodotDisplayVK.hide();
+	},
+
+	godot_js_display_vk_available__sig: 'i',
+	godot_js_display_vk_available: function () {
+		return GodotDisplayVK.available();
+	},
+
+	godot_js_display_vk_cb__sig: 'vi',
+	godot_js_display_vk_cb: function (p_input_cb) {
+		const input_cb = GodotRuntime.get_func(p_input_cb);
+		if (GodotDisplayVK.available()) {
+			GodotDisplayVK.init(input_cb);
+		}
 	},
 
 	/*
diff --git a/platform/javascript/js/libs/library_godot_fetch.js b/platform/javascript/js/libs/library_godot_fetch.js
new file mode 100644
index 0000000000..4ae6a23593
--- /dev/null
+++ b/platform/javascript/js/libs/library_godot_fetch.js
@@ -0,0 +1,258 @@
+/*************************************************************************/
+/*  library_godot_fetch.js                                               */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2021 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.                */
+/*************************************************************************/
+
+const GodotFetch = {
+	$GodotFetch__deps: ['$GodotRuntime'],
+	$GodotFetch: {
+
+		onread: function (id, result) {
+			const obj = IDHandler.get(id);
+			if (!obj) {
+				return;
+			}
+			if (result.value) {
+				obj.chunks.push(result.value);
+			}
+			obj.reading = false;
+			obj.done = result.done;
+		},
+
+		onresponse: function (id, response) {
+			const obj = IDHandler.get(id);
+			if (!obj) {
+				return;
+			}
+			let size = -1;
+			let compressed = false;
+			let chunked = false;
+			response.headers.forEach(function (value, header) {
+				const v = value.toLowerCase().trim();
+				const h = header.toLowerCase().trim();
+				if (h === 'content-encoding') {
+					compressed = true;
+					size = -1;
+				} else if (h === 'content-length') {
+					const len = Number.parseInt(value, 10);
+					if (!Number.isNaN(len) && !compressed) {
+						size = len;
+					}
+				} else if (h === 'transfer-encoding' && v === 'chunked') {
+					chunked = true;
+				}
+			});
+			obj.bodySize = size;
+			obj.status = response.status;
+			obj.response = response;
+			obj.reader = response.body.getReader();
+			obj.chunked = chunked;
+		},
+
+		onerror: function (id, err) {
+			GodotRuntime.error(err);
+			const obj = IDHandler.get(id);
+			if (!obj) {
+				return;
+			}
+			obj.error = err;
+		},
+
+		create: function (method, url, headers, body) {
+			const obj = {
+				request: null,
+				response: null,
+				reader: null,
+				error: null,
+				done: false,
+				reading: false,
+				status: 0,
+				chunks: [],
+				bodySize: -1,
+			};
+			const id = IDHandler.add(obj);
+			const init = {
+				method: method,
+				headers: headers,
+				body: body,
+			};
+			obj.request = fetch(url, init);
+			obj.request.then(GodotFetch.onresponse.bind(null, id)).catch(GodotFetch.onerror.bind(null, id));
+			return id;
+		},
+
+		free: function (id) {
+			const obj = IDHandler.get(id);
+			if (!obj) {
+				return;
+			}
+			IDHandler.remove(id);
+			if (!obj.request) {
+				return;
+			}
+			// Try to abort
+			obj.request.then(function (response) {
+				response.abort();
+			}).catch(function (e) { /* nothing to do */ });
+		},
+
+		read: function (id) {
+			const obj = IDHandler.get(id);
+			if (!obj) {
+				return;
+			}
+			if (obj.reader && !obj.reading) {
+				if (obj.done) {
+					obj.reader = null;
+					return;
+				}
+				obj.reading = true;
+				obj.reader.read().then(GodotFetch.onread.bind(null, id)).catch(GodotFetch.onerror.bind(null, id));
+			}
+		},
+	},
+
+	godot_js_fetch_create__sig: 'iii',
+	godot_js_fetch_create: function (p_method, p_url, p_headers, p_headers_size, p_body, p_body_size) {
+		const method = GodotRuntime.parseString(p_method);
+		const url = GodotRuntime.parseString(p_url);
+		const headers = GodotRuntime.parseStringArray(p_headers, p_headers_size);
+		const body = p_body_size ? GodotRuntime.heapSlice(HEAP8, p_body, p_body_size) : null;
+		return GodotFetch.create(method, url, headers.map(function (hv) {
+			const idx = hv.indexOf(':');
+			if (idx <= 0) {
+				return [];
+			}
+			return [
+				hv.slice(0, idx).trim(),
+				hv.slice(idx + 1).trim(),
+			];
+		}).filter(function (v) {
+			return v.length === 2;
+		}), body);
+	},
+
+	godot_js_fetch_state_get__sig: 'ii',
+	godot_js_fetch_state_get: function (p_id) {
+		const obj = IDHandler.get(p_id);
+		if (!obj) {
+			return -1;
+		}
+		if (obj.error) {
+			return -1;
+		}
+		if (!obj.response) {
+			return 0;
+		}
+		if (obj.reader) {
+			return 1;
+		}
+		if (obj.done) {
+			return 2;
+		}
+		return -1;
+	},
+
+	godot_js_fetch_http_status_get__sig: 'ii',
+	godot_js_fetch_http_status_get: function (p_id) {
+		const obj = IDHandler.get(p_id);
+		if (!obj || !obj.response) {
+			return 0;
+		}
+		return obj.status;
+	},
+
+	godot_js_fetch_read_headers__sig: 'iii',
+	godot_js_fetch_read_headers: function (p_id, p_parse_cb, p_ref) {
+		const obj = IDHandler.get(p_id);
+		if (!obj || !obj.response) {
+			return 1;
+		}
+		const cb = GodotRuntime.get_func(p_parse_cb);
+		const arr = [];
+		obj.response.headers.forEach(function (v, h) {
+			arr.push(`${h}:${v}`);
+		});
+		const c_ptr = GodotRuntime.allocStringArray(arr);
+		cb(arr.length, c_ptr, p_ref);
+		GodotRuntime.freeStringArray(c_ptr, arr.length);
+		return 0;
+	},
+
+	godot_js_fetch_read_chunk__sig: 'ii',
+	godot_js_fetch_read_chunk: function (p_id, p_buf, p_buf_size) {
+		const obj = IDHandler.get(p_id);
+		if (!obj || !obj.response) {
+			return 0;
+		}
+		let to_read = p_buf_size;
+		const chunks = obj.chunks;
+		while (to_read && chunks.length) {
+			const chunk = obj.chunks[0];
+			if (chunk.length > to_read) {
+				GodotRuntime.heapCopy(HEAP8, chunk.slice(0, to_read), p_buf);
+				chunks[0] = chunk.slice(to_read);
+				to_read = 0;
+			} else {
+				GodotRuntime.heapCopy(HEAP8, chunk, p_buf);
+				to_read -= chunk.length;
+				chunks.pop();
+			}
+		}
+		if (!chunks.length) {
+			GodotFetch.read(p_id);
+		}
+		return p_buf_size - to_read;
+	},
+
+	godot_js_fetch_body_length_get__sig: 'ii',
+	godot_js_fetch_body_length_get: function (p_id) {
+		const obj = IDHandler.get(p_id);
+		if (!obj || !obj.response) {
+			return -1;
+		}
+		return obj.bodySize;
+	},
+
+	godot_js_fetch_is_chunked__sig: 'ii',
+	godot_js_fetch_is_chunked: function (p_id) {
+		const obj = IDHandler.get(p_id);
+		if (!obj || !obj.response) {
+			return -1;
+		}
+		return obj.chunked ? 1 : 0;
+	},
+
+	godot_js_fetch_free__sig: 'vi',
+	godot_js_fetch_free: function (id) {
+		GodotFetch.free(id);
+	},
+};
+
+autoAddDeps(GodotFetch, '$GodotFetch');
+mergeInto(LibraryManager.library, GodotFetch);
diff --git a/platform/javascript/js/libs/library_godot_http_request.js b/platform/javascript/js/libs/library_godot_http_request.js
deleted file mode 100644
index 7dc2a2df29..0000000000
--- a/platform/javascript/js/libs/library_godot_http_request.js
+++ /dev/null
@@ -1,142 +0,0 @@
-/*************************************************************************/
-/*  http_request.js                                                      */
-/*************************************************************************/
-/*                       This file is part of:                           */
-/*                           GODOT ENGINE                                */
-/*                      https://godotengine.org                          */
-/*************************************************************************/
-/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
-/* Copyright (c) 2014-2021 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.                */
-/*************************************************************************/
-
-const GodotHTTPRequest = {
-	$GodotHTTPRequest__deps: ['$GodotRuntime'],
-	$GodotHTTPRequest: {
-		requests: [],
-
-		getUnusedRequestId: function () {
-			const idMax = GodotHTTPRequest.requests.length;
-			for (let potentialId = 0; potentialId < idMax; ++potentialId) {
-				if (GodotHTTPRequest.requests[potentialId] instanceof XMLHttpRequest) {
-					continue;
-				}
-				return potentialId;
-			}
-			GodotHTTPRequest.requests.push(null);
-			return idMax;
-		},
-
-		setupRequest: function (xhr) {
-			xhr.responseType = 'arraybuffer';
-		},
-	},
-
-	godot_xhr_new__sig: 'i',
-	godot_xhr_new: function () {
-		const newId = GodotHTTPRequest.getUnusedRequestId();
-		GodotHTTPRequest.requests[newId] = new XMLHttpRequest();
-		GodotHTTPRequest.setupRequest(GodotHTTPRequest.requests[newId]);
-		return newId;
-	},
-
-	godot_xhr_reset__sig: 'vi',
-	godot_xhr_reset: function (xhrId) {
-		GodotHTTPRequest.requests[xhrId] = new XMLHttpRequest();
-		GodotHTTPRequest.setupRequest(GodotHTTPRequest.requests[xhrId]);
-	},
-
-	godot_xhr_free__sig: 'vi',
-	godot_xhr_free: function (xhrId) {
-		GodotHTTPRequest.requests[xhrId].abort();
-		GodotHTTPRequest.requests[xhrId] = null;
-	},
-
-	godot_xhr_open__sig: 'viiiii',
-	godot_xhr_open: function (xhrId, method, url, p_user, p_password) {
-		const user = p_user > 0 ? GodotRuntime.parseString(p_user) : null;
-		const password = p_password > 0 ? GodotRuntime.parseString(p_password) : null;
-		GodotHTTPRequest.requests[xhrId].open(GodotRuntime.parseString(method), GodotRuntime.parseString(url), true, user, password);
-	},
-
-	godot_xhr_set_request_header__sig: 'viii',
-	godot_xhr_set_request_header: function (xhrId, header, value) {
-		GodotHTTPRequest.requests[xhrId].setRequestHeader(GodotRuntime.parseString(header), GodotRuntime.parseString(value));
-	},
-
-	godot_xhr_send__sig: 'viii',
-	godot_xhr_send: function (xhrId, p_ptr, p_len) {
-		let data = null;
-		if (p_ptr && p_len) {
-			data = GodotRuntime.heapCopy(HEAP8, p_ptr, p_len);
-		}
-		GodotHTTPRequest.requests[xhrId].send(data);
-	},
-
-	godot_xhr_abort__sig: 'vi',
-	godot_xhr_abort: function (xhrId) {
-		GodotHTTPRequest.requests[xhrId].abort();
-	},
-
-	godot_xhr_get_status__sig: 'ii',
-	godot_xhr_get_status: function (xhrId) {
-		return GodotHTTPRequest.requests[xhrId].status;
-	},
-
-	godot_xhr_get_ready_state__sig: 'ii',
-	godot_xhr_get_ready_state: function (xhrId) {
-		return GodotHTTPRequest.requests[xhrId].readyState;
-	},
-
-	godot_xhr_get_response_headers_length__sig: 'ii',
-	godot_xhr_get_response_headers_length: function (xhrId) {
-		const headers = GodotHTTPRequest.requests[xhrId].getAllResponseHeaders();
-		return headers === null ? 0 : GodotRuntime.strlen(headers);
-	},
-
-	godot_xhr_get_response_headers__sig: 'viii',
-	godot_xhr_get_response_headers: function (xhrId, dst, len) {
-		const str = GodotHTTPRequest.requests[xhrId].getAllResponseHeaders();
-		if (str === null) {
-			return;
-		}
-		GodotRuntime.stringToHeap(str, dst, len);
-	},
-
-	godot_xhr_get_response_length__sig: 'ii',
-	godot_xhr_get_response_length: function (xhrId) {
-		const body = GodotHTTPRequest.requests[xhrId].response;
-		return body === null ? 0 : body.byteLength;
-	},
-
-	godot_xhr_get_response__sig: 'viii',
-	godot_xhr_get_response: function (xhrId, dst, len) {
-		let buf = GodotHTTPRequest.requests[xhrId].response;
-		if (buf === null) {
-			return;
-		}
-		buf = new Uint8Array(buf).subarray(0, len);
-		HEAPU8.set(buf, dst);
-	},
-};
-
-autoAddDeps(GodotHTTPRequest, '$GodotHTTPRequest');
-mergeInto(LibraryManager.library, GodotHTTPRequest);
diff --git a/platform/javascript/js/libs/library_godot_os.js b/platform/javascript/js/libs/library_godot_os.js
index 9fde4a84e1..1d9f889bce 100644
--- a/platform/javascript/js/libs/library_godot_os.js
+++ b/platform/javascript/js/libs/library_godot_os.js
@@ -58,21 +58,34 @@ const GodotConfig = {
 	$GodotConfig: {
 		canvas: null,
 		locale: 'en',
-		resize_on_start: false,
+		canvas_resize_policy: 2, // Adaptive
+		virtual_keyboard: false,
+		persistent_drops: false,
 		on_execute: null,
+		on_exit: null,
 
 		init_config: function (p_opts) {
-			GodotConfig.resize_on_start = !!p_opts['resizeCanvasOnStart'];
+			GodotConfig.canvas_resize_policy = p_opts['canvasResizePolicy'];
 			GodotConfig.canvas = p_opts['canvas'];
 			GodotConfig.locale = p_opts['locale'] || GodotConfig.locale;
+			GodotConfig.virtual_keyboard = p_opts['virtualKeyboard'];
+			GodotConfig.persistent_drops = !!p_opts['persistentDrops'];
 			GodotConfig.on_execute = p_opts['onExecute'];
-			// This is called by emscripten, even if undocumented.
-			Module['onExit'] = p_opts['onExit']; // eslint-disable-line no-undef
+			GodotConfig.on_exit = p_opts['onExit'];
 		},
 
 		locate_file: function (file) {
 			return Module['locateFile'](file); // eslint-disable-line no-undef
 		},
+		clear: function () {
+			GodotConfig.canvas = null;
+			GodotConfig.locale = 'en';
+			GodotConfig.canvas_resize_policy = 2;
+			GodotConfig.virtual_keyboard = false;
+			GodotConfig.persistent_drops = false;
+			GodotConfig.on_execute = null;
+			GodotConfig.on_exit = null;
+		},
 	},
 
 	godot_js_config_canvas_id_get__sig: 'vii',
@@ -84,11 +97,6 @@ const GodotConfig = {
 	godot_js_config_locale_get: function (p_ptr, p_ptr_max) {
 		GodotRuntime.stringToHeap(GodotConfig.locale, p_ptr, p_ptr_max);
 	},
-
-	godot_js_config_is_resize_on_start__sig: 'i',
-	godot_js_config_is_resize_on_start: function () {
-		return GodotConfig.resize_on_start ? 1 : 0;
-	},
 };
 
 autoAddDeps(GodotConfig, '$GodotConfig');
@@ -98,7 +106,6 @@ const GodotFS = {
 	$GodotFS__deps: ['$FS', '$IDBFS', '$GodotRuntime'],
 	$GodotFS__postset: [
 		'Module["initFS"] = GodotFS.init;',
-		'Module["deinitFS"] = GodotFS.deinit;',
 		'Module["copyToFS"] = GodotFS.copy_to_fs;',
 	].join(''),
 	$GodotFS: {
@@ -210,9 +217,10 @@ const GodotFS = {
 mergeInto(LibraryManager.library, GodotFS);
 
 const GodotOS = {
-	$GodotOS__deps: ['$GodotFS', '$GodotRuntime'],
+	$GodotOS__deps: ['$GodotRuntime', '$GodotConfig', '$GodotFS'],
 	$GodotOS__postset: [
 		'Module["request_quit"] = function() { GodotOS.request_quit() };',
+		'Module["onExit"] = GodotOS.cleanup;',
 		'GodotOS._fs_sync_promise = Promise.resolve();',
 	].join(''),
 	$GodotOS: {
@@ -224,6 +232,15 @@ const GodotOS = {
 			GodotOS._async_cbs.push(p_promise_cb);
 		},
 
+		cleanup: function (exit_code) {
+			const cb = GodotConfig.on_exit;
+			GodotFS.deinit();
+			GodotConfig.clear();
+			if (cb) {
+				cb(exit_code);
+			}
+		},
+
 		finish_async: function (callback) {
 			GodotOS._fs_sync_promise.then(function (err) {
 				const promises = [];
@@ -282,6 +299,11 @@ const GodotOS = {
 	godot_js_os_shell_open: function (p_uri) {
 		window.open(GodotRuntime.parseString(p_uri), '_blank');
 	},
+
+	godot_js_os_hw_concurrency_get__sig: 'i',
+	godot_js_os_hw_concurrency_get: function () {
+		return navigator.hardwareConcurrency || 1;
+	},
 };
 
 autoAddDeps(GodotOS, '$GodotOS');
diff --git a/platform/javascript/js/libs/library_godot_runtime.js b/platform/javascript/js/libs/library_godot_runtime.js
index 7e36ff8ab5..3da1ed8f06 100644
--- a/platform/javascript/js/libs/library_godot_runtime.js
+++ b/platform/javascript/js/libs/library_godot_runtime.js
@@ -72,11 +72,16 @@ const GodotRuntime = {
 			return p_heap.subarray(p_ptr / bytes, p_ptr / bytes + p_len);
 		},
 
-		heapCopy: function (p_heap, p_ptr, p_len) {
+		heapSlice: function (p_heap, p_ptr, p_len) {
 			const bytes = p_heap.BYTES_PER_ELEMENT;
 			return p_heap.slice(p_ptr / bytes, p_ptr / bytes + p_len);
 		},
 
+		heapCopy: function (p_dst, p_src, p_ptr) {
+			const bytes = p_src.BYTES_PER_ELEMENT;
+			return p_dst.set(p_src, p_ptr / bytes);
+		},
+
 		/*
 		 * Strings
 		 */
@@ -84,6 +89,15 @@ const GodotRuntime = {
 			return UTF8ToString(p_ptr); // eslint-disable-line no-undef
 		},
 
+		parseStringArray: function (p_ptr, p_size) {
+			const strings = [];
+			const ptrs = GodotRuntime.heapSub(HEAP32, p_ptr, p_size); // TODO wasm64
+			ptrs.forEach(function (ptr) {
+				strings.push(GodotRuntime.parseString(ptr));
+			});
+			return strings;
+		},
+
 		strlen: function (p_str) {
 			return lengthBytesUTF8(p_str); // eslint-disable-line no-undef
 		},