[HTML5] Libraries refactor for linting.

Initial work to make liniting easier.

This includes:
- Rename http_request.js to library_godot_http_request.js.
- Rename externs.js to engine.externs.js.
- New library_godot_runtime.js (GodotRuntime) wraps around emscripten
  functions.
- Refactor of XMLHttpRequest handler in engine/preloader.js.
- Few fixes to bugs spotted by early stage linting.

14 files changed, 413 insertions, 312 deletions

diff --git a/platform/javascript/SCsub b/platform/javascript/SCsub
index a0e6fa0e18..627ae778b1 100644
--- a/platform/javascript/SCsub
+++ b/platform/javascript/SCsub
@@ -20,27 +20,28 @@ build = env.add_program(build_targets, javascript_files)
 
 env.AddJSLibraries(
     [
-        "native/http_request.js",
-        "native/library_godot_audio.js",
-        "native/library_godot_display.js",
-        "native/library_godot_os.js",
+        "js/libs/library_godot_audio.js",
+        "js/libs/library_godot_display.js",
+        "js/libs/library_godot_http_request.js",
+        "js/libs/library_godot_os.js",
+        "js/libs/library_godot_runtime.js",
     ]
 )
 
 if env["tools"]:
-    env.AddJSLibraries(["native/library_godot_editor_tools.js"])
+    env.AddJSLibraries(["js/libs/library_godot_editor_tools.js"])
 if env["javascript_eval"]:
-    env.AddJSLibraries(["native/library_godot_eval.js"])
+    env.AddJSLibraries(["js/libs/library_godot_eval.js"])
 for lib in env["JS_LIBS"]:
     env.Append(LINKFLAGS=["--js-library", lib])
 env.Depends(build, env["JS_LIBS"])
 
 engine = [
-    "engine/preloader.js",
-    "engine/utils.js",
-    "engine/engine.js",
+    "js/engine/preloader.js",
+    "js/engine/utils.js",
+    "js/engine/engine.js",
 ]
-externs = [env.File("#platform/javascript/engine/externs.js")]
+externs = [env.File("#platform/javascript/js/engine/engine.externs.js")]
 js_engine = env.CreateEngineFile("#bin/godot${PROGSUFFIX}.engine.js", engine, externs)
 env.Depends(js_engine, externs)
 
@@ -59,7 +60,7 @@ out_files = [
     zip_dir.File(binary_name + ".audio.worklet.js"),
 ]
 html_file = "#misc/dist/html/editor.html" if env["tools"] else "#misc/dist/html/full-size.html"
-in_files = [js_wrapped, build[1], html_file, "#platform/javascript/native/audio.worklet.js"]
+in_files = [js_wrapped, build[1], html_file, "#platform/javascript/js/libs/audio.worklet.js"]
 if env["threads_enabled"]:
     in_files.append(build[2])
     out_files.append(zip_dir.File(binary_name + ".worker.js"))
diff --git a/platform/javascript/engine/preloader.js b/platform/javascript/engine/preloader.js
deleted file mode 100644
index b3467d009f..0000000000
--- a/platform/javascript/engine/preloader.js
+++ /dev/null
@@ -1,135 +0,0 @@
-var Preloader = /** @constructor */ function() {
-	var DOWNLOAD_ATTEMPTS_MAX = 4;
-	var progressFunc = null;
-	var lastProgress = { loaded: 0, total: 0 };
-
-	var loadingFiles = {};
-	this.preloadedFiles = [];
-
-	function loadXHR(resolve, reject, file, tracker) {
-		var xhr = new XMLHttpRequest;
-		xhr.open('GET', file);
-		if (!file.endsWith('.js')) {
-			xhr.responseType = 'arraybuffer';
-		}
-		['loadstart', 'progress', 'load', 'error', 'abort'].forEach(function(ev) {
-			xhr.addEventListener(ev, onXHREvent.bind(xhr, resolve, reject, file, tracker));
-		});
-		xhr.send();
-	}
-
-	function onXHREvent(resolve, reject, file, tracker, ev) {
-		if (this.status >= 400) {
-			if (this.status < 500 || ++tracker[file].attempts >= DOWNLOAD_ATTEMPTS_MAX) {
-				reject(new Error("Failed loading file '" + file + "': " + this.statusText));
-				this.abort();
-				return;
-			} else {
-				setTimeout(loadXHR.bind(null, resolve, reject, file, tracker), 1000);
-			}
-		}
-
-		switch (ev.type) {
-			case 'loadstart':
-				if (tracker[file] === undefined) {
-					tracker[file] = {
-						total: ev.total,
-						loaded: ev.loaded,
-						attempts: 0,
-						final: false,
-					};
-				}
-				break;
-
-			case 'progress':
-				tracker[file].loaded = ev.loaded;
-				tracker[file].total = ev.total;
-				break;
-
-			case 'load':
-				tracker[file].final = true;
-				resolve(this);
-				break;
-
-			case 'error':
-				if (++tracker[file].attempts >= DOWNLOAD_ATTEMPTS_MAX) {
-					tracker[file].final = true;
-					reject(new Error("Failed loading file '" + file + "'"));
-				} else {
-					setTimeout(loadXHR.bind(null, resolve, reject, file, tracker), 1000);
-				}
-				break;
-
-			case 'abort':
-				tracker[file].final = true;
-				reject(new Error("Loading file '" + file + "' was aborted."));
-				break;
-		}
-	}
-
-	this.loadPromise = function(file) {
-		return new Promise(function(resolve, reject) {
-			loadXHR(resolve, reject, file, loadingFiles);
-		});
-	}
-
-	this.preload = function(pathOrBuffer, destPath) {
-		if (pathOrBuffer instanceof ArrayBuffer) {
-			pathOrBuffer = new Uint8Array(pathOrBuffer);
-		} else if (ArrayBuffer.isView(pathOrBuffer)) {
-			pathOrBuffer = new Uint8Array(pathOrBuffer.buffer);
-		}
-		if (pathOrBuffer instanceof Uint8Array) {
-			this.preloadedFiles.push({
-				path: destPath,
-				buffer: pathOrBuffer
-			});
-			return Promise.resolve();
-		} else if (typeof pathOrBuffer === 'string') {
-			var me = this;
-			return this.loadPromise(pathOrBuffer).then(function(xhr) {
-				me.preloadedFiles.push({
-					path: destPath || pathOrBuffer,
-					buffer: xhr.response
-				});
-				return Promise.resolve();
-			});
-		} else {
-			throw Promise.reject("Invalid object for preloading");
-		}
-	};
-
-	var animateProgress = function() {
-		var loaded = 0;
-		var total = 0;
-		var totalIsValid = true;
-		var progressIsFinal = true;
-
-		Object.keys(loadingFiles).forEach(function(file) {
-			const stat = loadingFiles[file];
-			if (!stat.final) {
-				progressIsFinal = false;
-			}
-			if (!totalIsValid || stat.total === 0) {
-				totalIsValid = false;
-				total = 0;
-			} else {
-				total += stat.total;
-			}
-			loaded += stat.loaded;
-		});
-		if (loaded !== lastProgress.loaded || total !== lastProgress.total) {
-			lastProgress.loaded = loaded;
-			lastProgress.total = total;
-			if (typeof progressFunc === 'function')
-				progressFunc(loaded, total);
-		}
-		if (!progressIsFinal)
-			requestAnimationFrame(animateProgress);
-	}
-	this.animateProgress = animateProgress; // Also exposed to start it.
-
-	this.setProgressFunc = function(callback) {
-		progressFunc = callback;
-	}
-};
diff --git a/platform/javascript/engine/externs.js b/platform/javascript/js/engine/engine.externs.js
index 1a94dd15ec..1a94dd15ec 100644
--- a/platform/javascript/engine/externs.js
+++ b/platform/javascript/js/engine/engine.externs.js
diff --git a/platform/javascript/engine/engine.js b/platform/javascript/js/engine/engine.js
index 3745e04479..792ec9cb28 100644
--- a/platform/javascript/engine/engine.js
+++ b/platform/javascript/js/engine/engine.js
@@ -1,4 +1,4 @@
-Function('return this')()['Engine'] = (function() {
+const Engine = (function() {
 	var preloader = new Preloader();
 
 	var wasmExt = '.wasm';
@@ -25,7 +25,7 @@ Function('return this')()['Engine'] = (function() {
 	};
 
 	/** @constructor */
-	function Engine() {
+	function Engine() { // eslint-disable-line no-shadow
 		this.canvas = null;
 		this.executableName = '';
 		this.rtenv = null;
@@ -90,6 +90,9 @@ Function('return this')()['Engine'] = (function() {
 
 			if (!(me.canvas instanceof HTMLCanvasElement)) {
 				me.canvas = Utils.findCanvas();
+				if (!me.canvas) {
+					return Promise.reject(new Error('No canvas found in page'));
+				}
 			}
 
 			// Canvas can grab focus on click, or key events won't work.
@@ -104,7 +107,7 @@ Function('return this')()['Engine'] = (function() {
 
 			// Until context restoration is implemented warn the user of context loss.
 			me.canvas.addEventListener('webglcontextlost', function(ev) {
-				alert("WebGL context lost, please reload the page");
+				alert("WebGL context lost, please reload the page"); // eslint-disable-line no-alert
 				ev.preventDefault();
 			}, false);
 
@@ -198,10 +201,11 @@ Function('return this')()['Engine'] = (function() {
 
 	Engine.prototype.setStdoutFunc = function(func) {
 		var print = function(text) {
+			let msg = text;
 			if (arguments.length > 1) {
-				text = Array.prototype.slice.call(arguments).join(" ");
+				msg = Array.prototype.slice.call(arguments).join(" ");
 			}
-			func(text);
+			func(msg);
 		};
 		if (this.rtenv)
 			this.rtenv.print = print;
@@ -210,9 +214,11 @@ Function('return this')()['Engine'] = (function() {
 
 	Engine.prototype.setStderrFunc = function(func) {
 		var printErr = function(text) {
-			if (arguments.length > 1)
-				text = Array.prototype.slice.call(arguments).join(" ");
-			func(text);
+			let msg = text
+			if (arguments.length > 1) {
+				msg = Array.prototype.slice.call(arguments).join(" ");
+			}
+			func(msg);
 		};
 		if (this.rtenv)
 			this.rtenv.printErr = printErr;
@@ -269,3 +275,4 @@ Function('return this')()['Engine'] = (function() {
 	Engine.prototype['requestQuit'] = Engine.prototype.requestQuit;
 	return Engine;
 })();
+if (typeof window !== 'undefined') window['Engine'] = Engine;
diff --git a/platform/javascript/js/engine/preloader.js b/platform/javascript/js/engine/preloader.js
new file mode 100644
index 0000000000..8641646e6e
--- /dev/null
+++ b/platform/javascript/js/engine/preloader.js
@@ -0,0 +1,129 @@
+var Preloader = /** @constructor */ function() { // eslint-disable-line no-unused-vars
+
+	const loadXHR = function(resolve, reject, file, tracker, attempts) {
+		const xhr = new XMLHttpRequest();
+		tracker[file] = {
+			total: 0,
+			loaded: 0,
+			final: false,
+		};
+		xhr.onerror = function() {
+			if (attempts <= 1) {
+				reject(new Error("Failed loading file '" + file + "'"));
+			} else {
+				setTimeout(function () {
+					loadXHR(resolve, reject, file, tracker, attempts - 1);
+				}, 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();
+	};
+
+	const DOWNLOAD_ATTEMPTS_MAX = 4;
+	const loadingFiles = {};
+	const lastProgress = { loaded: 0, total: 0 };
+	let progressFunc = null;
+
+	const animateProgress = function() {
+
+		var loaded = 0;
+		var total = 0;
+		var totalIsValid = true;
+		var progressIsFinal = true;
+
+		Object.keys(loadingFiles).forEach(function(file) {
+			const stat = loadingFiles[file];
+			if (!stat.final) {
+				progressIsFinal = false;
+			}
+			if (!totalIsValid || stat.total === 0) {
+				totalIsValid = false;
+				total = 0;
+			} else {
+				total += stat.total;
+			}
+			loaded += stat.loaded;
+		});
+		if (loaded !== lastProgress.loaded || total !== lastProgress.total) {
+			lastProgress.loaded = loaded;
+			lastProgress.total = total;
+			if (typeof progressFunc === 'function')
+				progressFunc(loaded, total);
+		}
+		if (!progressIsFinal)
+			requestAnimationFrame(animateProgress);
+	}
+
+	this.animateProgress = animateProgress;
+
+	this.setProgressFunc = function(callback) {
+		progressFunc = callback;
+	}
+
+
+	this.loadPromise = function(file) {
+		return new Promise(function(resolve, reject) {
+			loadXHR(resolve, reject, file, loadingFiles, DOWNLOAD_ATTEMPTS_MAX);
+		});
+	}
+
+	this.preloadedFiles = [];
+	this.preload = function(pathOrBuffer, destPath) {
+		let buffer = null;
+		if (typeof pathOrBuffer === 'string') {
+			var me = this;
+			return this.loadPromise(pathOrBuffer).then(function(xhr) {
+				me.preloadedFiles.push({
+					path: destPath || pathOrBuffer,
+					buffer: xhr.response
+				});
+				return Promise.resolve();
+			});
+		} else if (pathOrBuffer instanceof ArrayBuffer) {
+			buffer = new Uint8Array(pathOrBuffer);
+		} else if (ArrayBuffer.isView(pathOrBuffer)) {
+			buffer = new Uint8Array(pathOrBuffer.buffer);
+		}
+		if (buffer) {
+			this.preloadedFiles.push({
+				path: destPath,
+				buffer: pathOrBuffer
+			});
+			return Promise.resolve();
+		} else {
+			return Promise.reject(new Error("Invalid object for preloading"));
+		}
+	};
+};
diff --git a/platform/javascript/engine/utils.js b/platform/javascript/js/engine/utils.js
index 8455739a25..fbab9ba9f9 100644
--- a/platform/javascript/engine/utils.js
+++ b/platform/javascript/js/engine/utils.js
@@ -1,4 +1,5 @@
-var Utils = {
+var Utils = { // eslint-disable-line no-unused-vars
+
 	createLocateRewrite: function(execName) {
 		function rw(path) {
 			if (path.endsWith('.worker.js')) {
@@ -10,18 +11,20 @@ var Utils = {
 			} else if (path.endsWith('.wasm')) {
 				return execName + '.wasm';
 			}
+			return path;
 		}
 		return rw;
 	},
 
 	createInstantiatePromise: function(wasmLoader) {
+		let loader = wasmLoader;
 		function instantiateWasm(imports, onSuccess) {
-			wasmLoader.then(function(xhr) {
+			loader.then(function(xhr) {
 				WebAssembly.instantiate(xhr.response, imports).then(function(result) {
 					onSuccess(result['instance'], result['module']);
 				});
 			});
-			wasmLoader = null;
+			loader = null;
 			return {};
 		};
 
@@ -33,10 +36,11 @@ var Utils = {
 		if (nodes.length && nodes[0] instanceof HTMLCanvasElement) {
 			return nodes[0];
 		}
-		throw new Error("No canvas found");
+		return null;
 	},
 
 	isWebGLAvailable: function(majorVersion = 1) {
+
 		var testContext = false;
 		try {
 			var testCanvas = document.createElement('canvas');
@@ -45,7 +49,9 @@ var Utils = {
 			} else if (majorVersion === 2) {
 				testContext = testCanvas.getContext('webgl2') || testCanvas.getContext('experimental-webgl2');
 			}
-		} catch (e) {}
+		} catch (e) {
+			// Not available
+		}
 		return !!testContext;
 	}
 };
diff --git a/platform/javascript/native/audio.worklet.js b/platform/javascript/js/libs/audio.worklet.js
index f91787b993..a27035ef22 100644
--- a/platform/javascript/native/audio.worklet.js
+++ b/platform/javascript/js/libs/audio.worklet.js
@@ -27,6 +27,7 @@
 /* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
 /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
 /*************************************************************************/
+
 class RingBuffer {
 	constructor(p_buffer, p_state) {
 		this.buffer = p_buffer;
@@ -104,7 +105,7 @@ class GodotProcessor extends AudioWorkletProcessor {
 	}
 
 	parse_message(p_cmd, p_data) {
-		if (p_cmd == "start" && p_data) {
+		if (p_cmd === "start" && p_data) {
 			const state = p_data[0];
 			let idx = 0;
 			this.lock = state.subarray(idx, ++idx);
@@ -113,14 +114,14 @@ class GodotProcessor extends AudioWorkletProcessor {
 			const avail_out = state.subarray(idx, ++idx);
 			this.input = new RingBuffer(p_data[1], avail_in);
 			this.output = new RingBuffer(p_data[2], avail_out);
-		} else if (p_cmd == "stop") {
+		} else if (p_cmd === "stop") {
 			this.runing = false;
 			this.output = null;
 			this.input = null;
 		}
 	}
 
-	array_has_data(arr) {
+	static array_has_data(arr) {
 		return arr.length && arr[0].length && arr[0][0].length;
 	}
 
@@ -131,30 +132,30 @@ class GodotProcessor extends AudioWorkletProcessor {
 		if (this.output === null) {
 			return true; // Not ready yet, keep processing.
 		}
-		const process_input = this.array_has_data(inputs);
+		const process_input = GodotProcessor.array_has_data(inputs);
 		if (process_input) {
 			const input = inputs[0];
 			const chunk = input[0].length * input.length;
-			if (this.input_buffer.length != chunk) {
+			if (this.input_buffer.length !== chunk) {
 				this.input_buffer = new Float32Array(chunk);
 			}
 			if (this.input.space_left() >= chunk) {
-				this.write_input(this.input_buffer, input);
+				GodotProcessor.write_input(this.input_buffer, input);
 				this.input.write(this.input_buffer);
 			} else {
 				this.port.postMessage("Input buffer is full! Skipping input frame.");
 			}
 		}
-		const process_output = this.array_has_data(outputs);
+		const process_output = GodotProcessor.array_has_data(outputs);
 		if (process_output) {
 			const output = outputs[0];
 			const chunk = output[0].length * output.length;
-			if (this.output_buffer.length != chunk) {
+			if (this.output_buffer.length !== chunk) {
 				this.output_buffer = new Float32Array(chunk);
 			}
 			if (this.output.data_left() >= chunk) {
 				this.output.read(this.output_buffer);
-				this.write_output(output, this.output_buffer);
+				GodotProcessor.write_output(output, this.output_buffer);
 			} else {
 				this.port.postMessage("Output buffer has not enough frames! Skipping output frame.");
 			}
@@ -163,7 +164,7 @@ class GodotProcessor extends AudioWorkletProcessor {
 		return true;
 	}
 
-	write_output(dest, source) {
+	static write_output(dest, source) {
 		const channels = dest.length;
 		for (let ch = 0; ch < channels; ch++) {
 			for (let sample = 0; sample < dest[ch].length; sample++) {
@@ -172,7 +173,7 @@ class GodotProcessor extends AudioWorkletProcessor {
 		}
 	}
 
-	write_input(dest, source) {
+	static write_input(dest, source) {
 		const channels = source.length;
 		for (let ch = 0; ch < channels; ch++) {
 			for (let sample = 0; sample < source[ch].length; sample++) {
diff --git a/platform/javascript/native/library_godot_audio.js b/platform/javascript/js/libs/library_godot_audio.js
index 3a0c8f297a..a657d0a125 100644
--- a/platform/javascript/native/library_godot_audio.js
+++ b/platform/javascript/js/libs/library_godot_audio.js
@@ -29,7 +29,7 @@
 /*************************************************************************/
 
 const GodotAudio = {
-	$GodotAudio__deps: ['$GodotOS'],
+	$GodotAudio__deps: ['$GodotRuntime', '$GodotOS'],
 	$GodotAudio: {
 		ctx: null,
 		input: null,
@@ -42,7 +42,6 @@ const GodotAudio = {
 				// latencyHint: latency / 1000 // Do not specify, leave 'interactive' for good performance.
 			});
 			GodotAudio.ctx = ctx;
-			onstatechange(ctx.state); // Immeditately notify state.
 			ctx.onstatechange = function() {
 				let state = 0;
 				switch (ctx.state) {
@@ -55,19 +54,22 @@ const GodotAudio = {
 					case 'closed':
 						state = 2;
 						break;
+
+					// no default
 				}
 				onstatechange(state);
 			}
+			ctx.onstatechange(); // Immeditately notify state.
 			// Update computed latency
 			GodotAudio.interval = setInterval(function() {
-				let latency = 0;
+				let computed_latency = 0;
 				if (ctx.baseLatency) {
-					latency += GodotAudio.ctx.baseLatency;
+					computed_latency += GodotAudio.ctx.baseLatency;
 				}
 				if (ctx.outputLatency) {
-					latency += GodotAudio.ctx.outputLatency;
+					computed_latency += GodotAudio.ctx.outputLatency;
 				}
-				onlatencyupdate(latency);
+				onlatencyupdate(computed_latency);
 			}, 1000);
 			GodotOS.atexit(GodotAudio.close_async);
 			return ctx.destination.channelCount;
@@ -84,14 +86,14 @@ const GodotAudio = {
 			if (navigator.mediaDevices.getUserMedia) {
 				navigator.mediaDevices.getUserMedia({
 					"audio": true
-				}).then(gotMediaInput, function(e) { out(e) });
+				}).then(gotMediaInput, function(e) { GodotRuntime.print(e) });
 			} else {
 				if (!navigator.getUserMedia) {
 					navigator.getUserMedia = navigator.webkitGetUserMedia || navigator.mozGetUserMedia;
 				}
 				navigator.getUserMedia({
 					"audio": true
-				}, gotMediaInput, function(e) { out(e) });
+				}, gotMediaInput, function(e) { GodotRuntime.print(e) });
 			}
 		},
 
@@ -125,7 +127,7 @@ const GodotAudio = {
 				resolve();
 			}).catch(function(e) {
 				ctx.onstatechange = null;
-				console.error("Error closing AudioContext", e);
+				GodotRuntime.error("Error closing AudioContext", e);
 				resolve();
 			});
 		},
@@ -140,13 +142,13 @@ const GodotAudio = {
 	},
 
 	godot_audio_init: function(p_mix_rate, p_latency, p_state_change, p_latency_update) {
-		const statechange = GodotOS.get_func(p_state_change);
-		const latencyupdate = GodotOS.get_func(p_latency_update);
+		const statechange = GodotRuntime.get_func(p_state_change);
+		const latencyupdate = GodotRuntime.get_func(p_latency_update);
 		return GodotAudio.init(p_mix_rate, p_latency, statechange, latencyupdate);
 	},
 
 	godot_audio_resume: function() {
-		if (GodotAudio.ctx && GodotAudio.ctx.state != 'running') {
+		if (GodotAudio.ctx && GodotAudio.ctx.state !== 'running') {
 			GodotAudio.ctx.resume();
 		}
 	},
@@ -181,13 +183,13 @@ mergeInto(LibraryManager.library, GodotAudio);
  * The AudioWorklet API driver, used when threads are available.
  */
 const GodotAudioWorklet = {
-	$GodotAudioWorklet__deps: ['$GodotAudio'],
+	$GodotAudioWorklet__deps: ['$GodotAudio', '$GodotConfig'],
 	$GodotAudioWorklet: {
 		promise: null,
 		worklet: null,
 
 		create: function(channels) {
-			const path = Module['locateFile']('godot.audio.worklet.js');
+			const path = GodotConfig.locate_file('godot.audio.worklet.js');
 			GodotAudioWorklet.promise = GodotAudio.ctx.audioWorklet.addModule(path).then(function() {
 				GodotAudioWorklet.worklet = new AudioWorkletNode(
 					GodotAudio.ctx,
@@ -210,7 +212,7 @@ const GodotAudioWorklet = {
 					'data': [state, in_buf, out_buf],
 				});
 				node.port.onmessage = function(event) {
-					console.error(event.data);
+					GodotRuntime.error(event.data);
 				};
 			});
 		},
@@ -240,9 +242,9 @@ const GodotAudioWorklet = {
 	},
 
 	godot_audio_worklet_start: function(p_in_buf, p_in_size, p_out_buf, p_out_size, p_state) {
-		const out_buffer = GodotOS.heapSub(HEAPF32, p_out_buf, p_out_size);
-		const in_buffer = GodotOS.heapSub(HEAPF32, p_in_buf, p_in_size);
-		const state = GodotOS.heapSub(HEAP32, p_state, 4);
+		const out_buffer = GodotRuntime.heapSub(HEAPF32, p_out_buf, p_out_size);
+		const in_buffer = GodotRuntime.heapSub(HEAPF32, p_in_buf, p_in_size);
+		const state = GodotRuntime.heapSub(HEAP32, p_state, 4);
 		GodotAudioWorklet.start(in_buffer, out_buffer, state);
 	},
 
@@ -280,7 +282,7 @@ const GodotAudioScript = {
 		start: function(p_in_buf, p_in_size, p_out_buf, p_out_size, onprocess) {
 			GodotAudioScript.script.onaudioprocess = function(event) {
 				// Read input
-				const inb = GodotOS.heapSub(HEAPF32, p_in_buf, p_in_size);
+				const inb = GodotRuntime.heapSub(HEAPF32, p_in_buf, p_in_size);
 				const input = event.inputBuffer;
 				if (GodotAudio.input) {
 					const inlen = input.getChannelData(0).length;
@@ -296,7 +298,7 @@ const GodotAudioScript = {
 				onprocess();
 
 				// Write the output.
-				const outb = GodotOS.heapSub(HEAPF32, p_out_buf, p_out_size);
+				const outb = GodotRuntime.heapSub(HEAPF32, p_out_buf, p_out_size);
 				const output = event.outputBuffer;
 				const channels = output.numberOfChannels;
 				for (let ch = 0; ch < channels; ch++) {
@@ -329,7 +331,7 @@ const GodotAudioScript = {
 	},
 
 	godot_audio_script_start: function(p_in_buf, p_in_size, p_out_buf, p_out_size, p_cb) {
-		const onprocess = GodotOS.get_func(p_cb);
+		const onprocess = GodotRuntime.get_func(p_cb);
 		GodotAudioScript.start(p_in_buf, p_in_size, p_out_buf, p_out_size, onprocess);
 	},
 };
diff --git a/platform/javascript/native/library_godot_display.js b/platform/javascript/js/libs/library_godot_display.js
index 11bbfbc60d..28f63ba557 100644
--- a/platform/javascript/native/library_godot_display.js
+++ b/platform/javascript/js/libs/library_godot_display.js
@@ -33,13 +33,14 @@
  * Keeps track of registered event listeners so it can remove them on shutdown.
  */
 const GodotDisplayListeners = {
+	$GodotDisplayListeners__deps: ['$GodotOS'],
 	$GodotDisplayListeners__postset: 'GodotOS.atexit(function(resolve, reject) { GodotDisplayListeners.clear(); resolve(); });',
 	$GodotDisplayListeners: {
 		handlers: [],
 
 		has: function(target, event, method, capture) {
 			return GodotDisplayListeners.handlers.findIndex(function(e) {
-				return e.target === target && e.event === event && e.method === method && e.capture == capture;
+				return e.target === target && e.event === event && e.method === method && e.capture === capture;
 			}) !== -1;
 		},
 
@@ -47,11 +48,11 @@ const GodotDisplayListeners = {
 			if (GodotDisplayListeners.has(target, event, method, capture)) {
 				return;
 			}
-			function Handler(target, event, method, capture) {
-				this.target = target;
-				this.event = event;
-				this.method = method;
-				this.capture = capture;
+			function Handler(p_target, p_event, p_method, p_capture) {
+				this.target = p_target;
+				this.event = p_event;
+				this.method = p_method;
+				this.capture = p_capture;
 			};
 			GodotDisplayListeners.handlers.push(new Handler(target, event, method, capture));
 			target.addEventListener(event, method, capture);
@@ -89,7 +90,7 @@ const GodotDisplayDragDrop = {
 			} else if (entry.isFile) {
 				GodotDisplayDragDrop.add_file(entry);
 			} else {
-				console.error("Unrecognized entry...", entry);
+				GodotRuntime.error("Unrecognized entry...", entry);
 			}
 		},
 
@@ -124,19 +125,19 @@ const GodotDisplayDragDrop = {
 						resolve()
 					};
 					reader.onerror = function() {
-						console.log("Error reading file");
+						GodotRuntime.print("Error reading file");
 						reject();
 					}
 					reader.readAsArrayBuffer(file);
 				}, function(err) {
-					console.log("Error!");
+					GodotRuntime.print("Error!");
 					reject();
 				});
 			}));
 		},
 
 		process: function(resolve, reject) {
-			if (GodotDisplayDragDrop.promises.length == 0) {
+			if (GodotDisplayDragDrop.promises.length === 0) {
 				resolve();
 				return;
 			}
@@ -164,10 +165,10 @@ const GodotDisplayDragDrop = {
 					}
 				}
 			} else {
-				console.error("File upload not supported");
+				GodotRuntime.error("File upload not supported");
 			}
 			new Promise(GodotDisplayDragDrop.process).then(function() {
-				const DROP = "/tmp/drop-" + parseInt(Math.random() * Math.pow(2, 31)) + "/";
+				const DROP = "/tmp/drop-" + parseInt(Math.random() * (1 << 30), 10) + "/";
 				const drops = [];
 				const files = [];
 				FS.mkdir(DROP);
@@ -175,14 +176,14 @@ const GodotDisplayDragDrop = {
 					const path = elem['path'];
 					GodotFS.copy_to_fs(DROP + path, elem['data']);
 					let idx = path.indexOf("/");
-					if (idx == -1) {
+					if (idx === -1) {
 						// Root file
 						drops.push(DROP + path);
 					} else {
 						// Subdir
 						const sub = path.substr(0, idx);
 						idx = sub.indexOf("/");
-						if (idx < 0 && drops.indexOf(DROP + sub) == -1) {
+						if (idx < 0 && drops.indexOf(DROP + sub) === -1) {
 							drops.push(DROP + sub);
 						}
 					}
@@ -199,7 +200,7 @@ const GodotDisplayDragDrop = {
 					let idx = dir.lastIndexOf("/");
 					while (idx > 0) {
 						dir = dir.substr(0, idx);
-						if (dirs.indexOf(DROP + dir) == -1) {
+						if (dirs.indexOf(DROP + dir) === -1) {
 							dirs.push(DROP + dir);
 						}
 						idx = dir.lastIndexOf("/");
@@ -234,8 +235,8 @@ mergeInto(LibraryManager.library, GodotDisplayDragDrop);
  * Keeps track of cursor status and custom shapes.
  */
 const GodotDisplayCursor = {
+	$GodotDisplayCursor__deps: ['$GodotOS', '$GodotConfig'],
 	$GodotDisplayCursor__postset: 'GodotOS.atexit(function(resolve, reject) { GodotDisplayCursor.clear(); resolve(); });',
-	$GodotDisplayCursor__deps: ['$GodotConfig', '$GodotOS'],
 	$GodotDisplayCursor: {
 		shape: 'auto',
 		visible: true,
@@ -273,7 +274,7 @@ mergeInto(LibraryManager.library, GodotDisplayCursor);
  * Exposes all the functions needed by DisplayServer implementation.
  */
 const GodotDisplay = {
-	$GodotDisplay__deps: ['$GodotConfig', '$GodotOS', '$GodotDisplayCursor', '$GodotDisplayListeners', '$GodotDisplayDragDrop'],
+	$GodotDisplay__deps: ['$GodotConfig', '$GodotRuntime', '$GodotDisplayCursor', '$GodotDisplayListeners', '$GodotDisplayDragDrop'],
 	$GodotDisplay: {
 		window_icon: '',
 	},
@@ -288,7 +289,7 @@ const GodotDisplay = {
 	},
 
 	godot_js_display_alert: function(p_text) {
-		window.alert(UTF8ToString(p_text));
+		window.alert(GodotRuntime.parseString(p_text)); // eslint-disable-line no-alert
 	},
 
 	godot_js_display_pixel_ratio_get: function() {
@@ -303,13 +304,13 @@ const GodotDisplay = {
 	},
 
 	godot_js_display_canvas_is_focused: function() {
-		return document.activeElement == GodotConfig.canvas;
+		return document.activeElement === GodotConfig.canvas;
 	},
 
 	godot_js_display_canvas_bounding_rect_position_get: function(r_x, r_y) {
 		const brect = GodotConfig.canvas.getBoundingClientRect();
-		setValue(r_x, brect.x, 'i32');
-		setValue(r_y, brect.y, 'i32');
+		GodotRuntime.setHeapValue(r_x, brect.x, 'i32');
+		GodotRuntime.setHeapValue(r_y, brect.y, 'i32');
 	},
 
 	/*
@@ -323,25 +324,24 @@ const GodotDisplay = {
 	 * Clipboard
 	 */
 	godot_js_display_clipboard_set: function(p_text) {
-		const text = UTF8ToString(p_text);
+		const text = GodotRuntime.parseString(p_text);
 		if (!navigator.clipboard || !navigator.clipboard.writeText) {
 			return 1;
 		}
 		navigator.clipboard.writeText(text).catch(function(e) {
 			// Setting OS clipboard is only possible from an input callback.
-			console.error("Setting OS clipboard is only possible from an input callback for the HTML5 plafrom. Exception:", e);
+			GodotRuntime.error("Setting OS clipboard is only possible from an input callback for the HTML5 plafrom. Exception:", e);
 		});
 		return 0;
 	},
 
-	godot_js_display_clipboard_get_deps: ['$GodotOS'],
 	godot_js_display_clipboard_get: function(callback) {
-		const func = GodotOS.get_func(callback);
+		const func = GodotRuntime.get_func(callback);
 		try {
 			navigator.clipboard.readText().then(function (result) {
-				const ptr = allocate(intArrayFromString(result), ALLOC_NORMAL);
+				const ptr = GodotRuntime.allocString(result);
 				func(ptr);
-				_free(ptr);
+				GodotRuntime.free(ptr);
 			}).catch(function (e) {
 				// Fail graciously.
 			});
@@ -362,7 +362,7 @@ const GodotDisplay = {
 	},
 
 	godot_js_display_window_title_set: function(p_data) {
-		document.title = UTF8ToString(p_data);
+		document.title = GodotRuntime.parseString(p_data);
 	},
 
 	godot_js_display_window_icon_set: function(p_ptr, p_len) {
@@ -374,7 +374,7 @@ const GodotDisplay = {
 			document.head.appendChild(link);
 		}
 		const old_icon = GodotDisplay.window_icon;
-		const png = new Blob([GodotOS.heapCopy(HEAPU8, p_ptr, p_len)], { type: "image/png" });
+		const png = new Blob([GodotRuntime.heapCopy(HEAPU8, p_ptr, p_len)], { type: "image/png" });
 		GodotDisplay.window_icon = URL.createObjectURL(png);
 		link.href = GodotDisplay.window_icon;
 		if (old_icon) {
@@ -386,8 +386,8 @@ const GodotDisplay = {
 	 * Cursor
 	 */
 	godot_js_display_cursor_set_visible: function(p_visible) {
-		const visible = p_visible != 0;
-		if (visible == GodotDisplayCursor.visible) {
+		const visible = p_visible !== 0;
+		if (visible === GodotDisplayCursor.visible) {
 			return;
 		}
 		GodotDisplayCursor.visible = visible;
@@ -403,14 +403,14 @@ const GodotDisplay = {
 	},
 
 	godot_js_display_cursor_set_shape: function(p_string) {
-		GodotDisplayCursor.set_shape(UTF8ToString(p_string));
+		GodotDisplayCursor.set_shape(GodotRuntime.parseString(p_string));
 	},
 
 	godot_js_display_cursor_set_custom_shape: function(p_shape, p_ptr, p_len, p_hotspot_x, p_hotspot_y) {
-		const shape = UTF8ToString(p_shape);
+		const shape = GodotRuntime.parseString(p_shape);
 		const old_shape = GodotDisplayCursor.cursors[shape];
 		if (p_len > 0) {
-			const png = new Blob([GodotOS.heapCopy(HEAPU8, p_ptr, p_len)], { type: 'image/png' });
+			const png = new Blob([GodotRuntime.heapCopy(HEAPU8, p_ptr, p_len)], { type: 'image/png' });
 			const url = URL.createObjectURL(png);
 			GodotDisplayCursor.cursors[shape] = {
 				url: url,
@@ -420,7 +420,7 @@ const GodotDisplay = {
 		} else {
 			delete GodotDisplayCursor.cursors[shape];
 		}
-		if (shape == GodotDisplayCursor.shape) {
+		if (shape === GodotDisplayCursor.shape) {
 			GodotDisplayCursor.set_shape(GodotDisplayCursor.shape);
 		}
 		if (old_shape) {
@@ -433,7 +433,7 @@ const GodotDisplay = {
 	 */
 	godot_js_display_notification_cb: function(callback, p_enter, p_exit, p_in, p_out) {
 		const canvas = GodotConfig.canvas;
-		const func = GodotOS.get_func(callback);
+		const func = GodotRuntime.get_func(callback);
 		const notif = [p_enter, p_exit, p_in, p_out];
 		['mouseover', 'mouseleave', 'focus', 'blur'].forEach(function(evt_name, idx) {
 			GodotDisplayListeners.add(canvas, evt_name, function() {
@@ -443,26 +443,26 @@ const GodotDisplay = {
 	},
 
 	godot_js_display_paste_cb: function(callback) {
-		const func = GodotOS.get_func(callback);
+		const func = GodotRuntime.get_func(callback);
 		GodotDisplayListeners.add(window, 'paste', function(evt) {
 			const text = evt.clipboardData.getData('text');
-			const ptr = allocate(intArrayFromString(text), ALLOC_NORMAL);
+			const ptr = GodotRuntime.allocString(text);
 			func(ptr);
-			_free(ptr);
+			GodotRuntime.free(ptr);
 		}, false);
 	},
 
 	godot_js_display_drop_files_cb: function(callback) {
-		const func = GodotOS.get_func(callback)
+		const func = GodotRuntime.get_func(callback)
 		const dropFiles = function(files) {
 			const args = files || [];
 			if (!args.length) {
 				return;
 			}
 			const argc = args.length;
-			const argv = GodotOS.allocStringArray(args);
+			const argv = GodotRuntime.allocStringArray(args);
 			func(argv, argc);
-			GodotOS.freeStringArray(argv, argc);
+			GodotRuntime.freeStringArray(argv, argc);
 		};
 		const canvas = GodotConfig.canvas;
 		GodotDisplayListeners.add(canvas, 'dragover', function(ev) {
diff --git a/platform/javascript/native/library_godot_editor_tools.js b/platform/javascript/js/libs/library_godot_editor_tools.js
index 202a198adb..21e40185ae 100644
--- a/platform/javascript/native/library_godot_editor_tools.js
+++ b/platform/javascript/js/libs/library_godot_editor_tools.js
@@ -31,9 +31,9 @@
 const GodotEditorTools = {
 	godot_js_editor_download_file__deps: ['$FS'],
 	godot_js_editor_download_file: function(p_path, p_name, p_mime) {
-		const path = UTF8ToString(p_path);
-		const name = UTF8ToString(p_name);
-		const mime = UTF8ToString(p_mime);
+		const path = GodotRuntime.parseString(p_path);
+		const name = GodotRuntime.parseString(p_name);
+		const mime = GodotRuntime.parseString(p_mime);
 		const size = FS.stat(path)['size'];
 		const buf = new Uint8Array(size);
 		const fd = FS.open(path, 'r');
diff --git a/platform/javascript/native/library_godot_eval.js b/platform/javascript/js/libs/library_godot_eval.js
index 44d356a4fb..4064938d3e 100644
--- a/platform/javascript/native/library_godot_eval.js
+++ b/platform/javascript/js/libs/library_godot_eval.js
@@ -29,34 +29,34 @@
 /*************************************************************************/
 
 const GodotEval = {
-	godot_js_eval__deps: ['$GodotOS'],
+	godot_js_eval__deps: ['$GodotRuntime'],
 	godot_js_eval: function(p_js, p_use_global_ctx, p_union_ptr, p_byte_arr, p_byte_arr_write, p_callback) {
-		const js_code = UTF8ToString(p_js);
+		const js_code = GodotRuntime.parseString(p_js);
 		let eval_ret = null;
 		try {
 			if (p_use_global_ctx) {
 				// indirect eval call grants global execution context
-				const global_eval = eval;
+				const global_eval = eval; // eslint-disable-line no-eval
 				eval_ret = global_eval(js_code);
 			} else {
-				eval_ret = eval(js_code);
+				eval_ret = eval(js_code); // eslint-disable-line no-eval
 			}
 		} catch (e) {
-			err(e);
+			GodotRuntime.error(e);
 		}
 
 		switch (typeof eval_ret) {
+
 			case 'boolean':
-				setValue(p_union_ptr, eval_ret, 'i32');
+				GodotRuntime.setHeapValue(p_union_ptr, eval_ret, 'i32');
 				return 1; // BOOL
 
 			case 'number':
-				setValue(p_union_ptr, eval_ret, 'double');
+				GodotRuntime.setHeapValue(p_union_ptr, eval_ret, 'double');
 				return 3; // REAL
 
 			case 'string':
-				let array_ptr = GodotOS.allocString(eval_ret);
-				setValue(p_union_ptr, array_ptr , '*');
+				GodotRuntime.setHeapValue(p_union_ptr, GodotRuntime.allocString(eval_ret), '*');
 				return 4; // STRING
 
 			case 'object':
@@ -71,12 +71,14 @@ const GodotEval = {
 					eval_ret = new Uint8Array(eval_ret);
 				}
 				if (eval_ret instanceof Uint8Array) {
-					const func = GodotOS.get_func(p_callback);
+					const func = GodotRuntime.get_func(p_callback);
 					const bytes_ptr = func(p_byte_arr, p_byte_arr_write,  eval_ret.length);
 					HEAPU8.set(eval_ret, bytes_ptr);
 					return 20; // POOL_BYTE_ARRAY
 				}
 				break;
+
+			// no default
 		}
 		return 0; // NIL
 	},
diff --git a/platform/javascript/native/http_request.js b/platform/javascript/js/libs/library_godot_http_request.js
index 272154aee3..6f80f3b958 100644
--- a/platform/javascript/native/http_request.js
+++ b/platform/javascript/js/libs/library_godot_http_request.js
@@ -27,7 +27,9 @@
 /* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
 /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
 /*************************************************************************/
-var GodotHTTPRequest = {
+
+const GodotHTTPRequest = {
+	$GodotHTTPRequest__deps: ['$GodotRuntime'],
 	$GodotHTTPRequest: {
 		requests: [],
 
@@ -65,14 +67,14 @@ var GodotHTTPRequest = {
 		GodotHTTPRequest.requests[xhrId] = null;
 	},
 
-	godot_xhr_open: function(xhrId, method, url, user, password) {
-		user = user > 0 ? UTF8ToString(user) : null;
-		password = password > 0 ? UTF8ToString(password) : null;
-		GodotHTTPRequest.requests[xhrId].open(UTF8ToString(method), UTF8ToString(url), true, user, password);
+	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: function(xhrId, header, value) {
-		GodotHTTPRequest.requests[xhrId].setRequestHeader(UTF8ToString(header), UTF8ToString(value));
+		GodotHTTPRequest.requests[xhrId].setRequestHeader(GodotRuntime.parseString(header), GodotRuntime.parseString(value));
 	},
 
 	godot_xhr_send_null: function(xhrId) {
@@ -81,19 +83,19 @@ var GodotHTTPRequest = {
 
 	godot_xhr_send_string: function(xhrId, strPtr) {
 		if (!strPtr) {
-			err("Failed to send string per XHR: null pointer");
+			GodotRuntime.error("Failed to send string per XHR: null pointer");
 			return;
 		}
-		GodotHTTPRequest.requests[xhrId].send(UTF8ToString(strPtr));
+		GodotHTTPRequest.requests[xhrId].send(GodotRuntime.parseString(strPtr));
 	},
 
 	godot_xhr_send_data: function(xhrId, ptr, len) {
 		if (!ptr) {
-			err("Failed to send data per XHR: null pointer");
+			GodotRuntime.error("Failed to send data per XHR: null pointer");
 			return;
 		}
 		if (len < 0) {
-			err("Failed to send data per XHR: buffer length less than 0");
+			GodotRuntime.error("Failed to send data per XHR: buffer length less than 0");
 			return;
 		}
 		GodotHTTPRequest.requests[xhrId].send(HEAPU8.subarray(ptr, ptr + len));
@@ -113,17 +115,14 @@ var GodotHTTPRequest = {
 
 	godot_xhr_get_response_headers_length: function(xhrId) {
 		var headers = GodotHTTPRequest.requests[xhrId].getAllResponseHeaders();
-		return headers === null ? 0 : lengthBytesUTF8(headers);
+		return headers === null ? 0 : GodotRuntime.strlen(headers);
 	},
 
 	godot_xhr_get_response_headers: function(xhrId, dst, len) {
 		var str = GodotHTTPRequest.requests[xhrId].getAllResponseHeaders();
 		if (str === null)
 			return;
-		var buf = new Uint8Array(len + 1);
-		stringToUTF8Array(str, buf, 0, buf.length);
-		buf = buf.subarray(0, -1);
-		HEAPU8.set(buf, dst);
+		GodotRuntime.stringToHeap(str, dst, len);
 	},
 
 	godot_xhr_get_response_length: function(xhrId) {
diff --git a/platform/javascript/native/library_godot_os.js b/platform/javascript/js/libs/library_godot_os.js
index a1424a691a..582f04cb1b 100644
--- a/platform/javascript/native/library_godot_os.js
+++ b/platform/javascript/js/libs/library_godot_os.js
@@ -54,6 +54,7 @@ mergeInto(LibraryManager.library, IDHandler);
 
 const GodotConfig = {
 	$GodotConfig__postset: 'Module["initConfig"] = GodotConfig.init_config;',
+	$GodotConfig__deps: ['$GodotRuntime'],
 	$GodotConfig: {
 		canvas: null,
 		locale: "en",
@@ -66,16 +67,20 @@ const GodotConfig = {
 			GodotConfig.locale = p_opts['locale'] || GodotConfig.locale;
 			GodotConfig.on_execute = p_opts['onExecute'];
 			// This is called by emscripten, even if undocumented.
-			Module['onExit'] = p_opts['onExit'];
+			Module['onExit'] = p_opts['onExit']; // eslint-disable-line no-undef
+		},
+
+		locate_file: function(file) {
+			return Module["locateFile"](file); // eslint-disable-line no-undef
 		},
 	},
 
 	godot_js_config_canvas_id_get: function(p_ptr, p_ptr_max) {
-		stringToUTF8('#' + GodotConfig.canvas.id, p_ptr, p_ptr_max);
+		GodotRuntime.stringToHeap('#' + GodotConfig.canvas.id, p_ptr, p_ptr_max);
 	},
 
 	godot_js_config_locale_get: function(p_ptr, p_ptr_max) {
-		stringToUTF8(GodotConfig.locale, p_ptr, p_ptr_max);
+		GodotRuntime.stringToHeap(GodotConfig.locale, p_ptr, p_ptr_max);
 	},
 
 	godot_js_config_is_resize_on_start: function() {
@@ -86,8 +91,9 @@ const GodotConfig = {
 autoAddDeps(GodotConfig, '$GodotConfig');
 mergeInto(LibraryManager.library, GodotConfig);
 
+
 const GodotFS = {
-	$GodotFS__deps: ['$FS', '$IDBFS'],
+	$GodotFS__deps: ['$FS', '$IDBFS', '$GodotRuntime'],
 	$GodotFS__postset: [
 		'Module["initFS"] = GodotFS.init;',
 		'Module["deinitFS"] = GodotFS.deinit;',
@@ -136,7 +142,7 @@ const GodotFS = {
 					if (err) {
 						GodotFS._mount_points = [];
 						GodotFS._idbfs = false;
-						console.log("IndexedDB not available: " + err.message);
+						GodotRuntime.print("IndexedDB not available: " + err.message);
 					} else {
 						GodotFS._idbfs = true;
 					}
@@ -151,7 +157,7 @@ const GodotFS = {
 				try {
 					FS.unmount(path);
 				} catch (e) {
-					console.log("Already unmounted", e);
+					GodotRuntime.print("Already unmounted", e);
 				}
 				if (GodotFS._idbfs && IDBFS.dbs[path]) {
 					IDBFS.dbs[path].close();
@@ -165,14 +171,14 @@ const GodotFS = {
 
 		sync: function() {
 			if (GodotFS._syncing) {
-				err('Already syncing!');
+				GodotRuntime.error('Already syncing!');
 				return Promise.resolve();
 			}
 			GodotFS._syncing = true;
 			return new Promise(function (resolve, reject) {
 				FS.syncfs(false, function(error) {
 					if (error) {
-						err('Failed to save IDB file system: ' + error.message);
+						GodotRuntime.error('Failed to save IDB file system: ' + error.message);
 					}
 					GodotFS._syncing = false;
 					resolve(error);
@@ -202,7 +208,7 @@ const GodotFS = {
 mergeInto(LibraryManager.library, GodotFS);
 
 const GodotOS = {
-	$GodotOS__deps: ['$GodotFS'],
+	$GodotOS__deps: ['$GodotFS', '$GodotRuntime'],
 	$GodotOS__postset: [
 		'Module["request_quit"] = function() { GodotOS.request_quit() };',
 		'GodotOS._fs_sync_promise = Promise.resolve();',
@@ -212,10 +218,6 @@ const GodotOS = {
 		_async_cbs: [],
 		_fs_sync_promise: null,
 
-		get_func: function(ptr) {
-			return wasmTable.get(ptr);
-		},
-
 		atexit: function(p_promise_cb) {
 			GodotOS._async_cbs.push(p_promise_cb);
 		},
@@ -236,48 +238,15 @@ const GodotOS = {
 				}, 0);
 			});
 		},
-
-		allocString: function(p_str) {
-			const length = lengthBytesUTF8(p_str)+1;
-			const c_str = _malloc(length);
-			stringToUTF8(p_str, c_str, length);
-			return c_str;
-		},
-
-		allocStringArray: function(strings) {
-			const size = strings.length;
-			const c_ptr = _malloc(size * 4);
-			for (let i = 0; i < size; i++) {
-				HEAP32[(c_ptr >> 2) + i] = GodotOS.allocString(strings[i]);
-			}
-			return c_ptr;
-		},
-
-		freeStringArray: function(c_ptr, size) {
-			for (let i = 0; i < size; i++) {
-				_free(HEAP32[(c_ptr >> 2) + i]);
-			}
-			_free(c_ptr);
-		},
-
-		heapSub: function(heap, ptr, size) {
-			const bytes = heap.BYTES_PER_ELEMENT;
-			return heap.subarray(ptr / bytes, ptr / bytes + size);
-		},
-
-		heapCopy: function(heap, ptr, size) {
-			const bytes = heap.BYTES_PER_ELEMENT;
-			return heap.slice(ptr / bytes, ptr / bytes + size);
-		},
 	},
 
 	godot_js_os_finish_async: function(p_callback) {
-		const func = GodotOS.get_func(p_callback);
+		const func = GodotRuntime.get_func(p_callback);
 		GodotOS.finish_async(func);
 	},
 
 	godot_js_os_request_quit_cb: function(p_callback) {
-		GodotOS.request_quit = GodotOS.get_func(p_callback);
+		GodotOS.request_quit = GodotRuntime.get_func(p_callback);
 	},
 
 	godot_js_os_fs_is_persistent: function() {
@@ -285,7 +254,7 @@ const GodotOS = {
 	},
 
 	godot_js_os_fs_sync: function(callback) {
-		const func = GodotOS.get_func(callback);
+		const func = GodotRuntime.get_func(callback);
 		GodotOS._fs_sync_promise = GodotFS.sync();
 		GodotOS._fs_sync_promise.then(function(err) {
 			func();
@@ -293,7 +262,7 @@ const GodotOS = {
 	},
 
 	godot_js_os_execute: function(p_json) {
-		const json_args = UTF8ToString(p_json);
+		const json_args = GodotRuntime.parseString(p_json);
 		const args = JSON.parse(json_args);
 		if (GodotConfig.on_execute) {
 			GodotConfig.on_execute(args);
@@ -303,7 +272,7 @@ const GodotOS = {
 	},
 
 	godot_js_os_shell_open: function(p_uri) {
-		window.open(UTF8ToString(p_uri), '_blank');
+		window.open(GodotRuntime.parseString(p_uri), '_blank');
 	},
 };
 
diff --git a/platform/javascript/js/libs/library_godot_runtime.js b/platform/javascript/js/libs/library_godot_runtime.js
new file mode 100644
index 0000000000..1769f83623
--- /dev/null
+++ b/platform/javascript/js/libs/library_godot_runtime.js
@@ -0,0 +1,120 @@
+/*************************************************************************/
+/*  library_godot_runtime.js                                             */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2020 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2020 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 GodotRuntime = {
+	$GodotRuntime: {
+		/*
+		 * Functions
+		 */
+		get_func: function(ptr) {
+			return wasmTable.get(ptr); // eslint-disable-line no-undef
+		},
+
+		/*
+		 * Prints
+		 */
+		error: function() {
+			err.apply(null, Array.from(arguments)); // eslint-disable-line no-undef
+		},
+
+		print: function() {
+			out.apply(null, Array.from(arguments)); // eslint-disable-line no-undef
+		},
+
+		/*
+		 * Memory
+		 */
+		malloc: function(p_size) {
+			return _malloc(p_size); // eslint-disable-line no-undef
+		},
+
+		free: function(p_ptr) {
+			_free(p_ptr); // eslint-disable-line no-undef
+		},
+
+		getHeapValue: function (p_ptr, p_type) {
+			return getValue(p_ptr, p_type); // eslint-disable-line no-undef
+		},
+
+		setHeapValue: function(p_ptr, p_value, p_type) {
+			setValue(p_ptr, p_value, p_type); // eslint-disable-line no-undef
+		},
+
+		heapSub: function(p_heap, p_ptr, p_len) {
+			const bytes = p_heap.BYTES_PER_ELEMENT;
+			return p_heap.subarray(p_ptr / bytes, p_ptr / bytes + p_len);
+		},
+
+		heapCopy: 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);
+		},
+
+		/*
+		 * Strings
+		 */
+		parseString: function(p_ptr) {
+			return UTF8ToString(p_ptr); // eslint-disable-line no-undef
+		},
+
+		strlen: function(p_str) {
+			return lengthBytesUTF8(p_str); // eslint-disable-line no-undef
+		},
+
+		allocString: function(p_str) {
+			const length = GodotRuntime.strlen(p_str)+1;
+			const c_str = GodotRuntime.malloc(length);
+			stringToUTF8(p_str, c_str, length); // eslint-disable-line no-undef
+			return c_str;
+		},
+
+		allocStringArray: function(p_strings) {
+			const size = p_strings.length;
+			const c_ptr = GodotRuntime.malloc(size * 4);
+			for (let i = 0; i < size; i++) {
+				HEAP32[(c_ptr >> 2) + i] = GodotRuntime.allocString(p_strings[i]);
+			}
+			return c_ptr;
+		},
+
+		freeStringArray: function(p_ptr, p_len) {
+			for (let i = 0; i < p_len; i++) {
+				GodotRuntime.free(HEAP32[(p_ptr >> 2) + i]);
+			}
+			GodotRuntime.free(p_ptr);
+		},
+
+		stringToHeap: function (p_str, p_ptr, p_len) {
+			return stringToUTF8Array(p_str, HEAP8, p_ptr, p_len); // eslint-disable-line no-undef
+		},
+	},
+};
+autoAddDeps(GodotRuntime, "$GodotRuntime");
+mergeInto(LibraryManager.library, GodotRuntime);