diff --git a/wasm/wasm_exec.js b/wasm/wasm_exec.js
index 165d567..a54bb9a 100644
--- a/wasm/wasm_exec.js
+++ b/wasm/wasm_exec.js
@@ -3,6 +3,15 @@
 // license that can be found in the LICENSE file.
 
 (() => {
+	// Map multiple JavaScript environments to a single common API,
+	// preferring web standards over Node.js API.
+	//
+	// Environments considered:
+	// - Browsers
+	// - Node.js
+	// - Electron
+	// - Parcel
+
 	if (typeof global !== "undefined") {
 		// global already exists
 	} else if (typeof window !== "undefined") {
@@ -13,30 +22,15 @@
 		throw new Error("cannot export Go (neither global, window nor self is defined)");
 	}
 
-	// Map web browser API and Node.js API to a single common API (preferring web standards over Node.js API).
-	const isNodeJS = global.process && global.process.title === "node";
-	if (isNodeJS) {
+	if (!global.require && typeof require !== "undefined") {
 		global.require = require;
+	}
+
+	if (!global.fs && global.require) {
 		global.fs = require("fs");
+	}
 
-		const nodeCrypto = require("crypto");
-		global.crypto = {
-			getRandomValues(b) {
-				nodeCrypto.randomFillSync(b);
-			},
-		};
-
-		global.performance = {
-			now() {
-				const [sec, nsec] = process.hrtime();
-				return sec * 1000 + nsec / 1000000;
-			},
-		};
-
-		const util = require("util");
-		global.TextEncoder = util.TextEncoder;
-		global.TextDecoder = util.TextDecoder;
-	} else {
+	if (!global.fs) {
 		let outputBuf = "";
 		global.fs = {
 			constants: { O_WRONLY: -1, O_RDWR: -1, O_CREAT: -1, O_TRUNC: -1, O_APPEND: -1, O_EXCL: -1 }, // unused
@@ -72,6 +66,34 @@
 		};
 	}
 
+	if (!global.crypto) {
+		const nodeCrypto = require("crypto");
+		global.crypto = {
+			getRandomValues(b) {
+				nodeCrypto.randomFillSync(b);
+			},
+		};
+	}
+
+	if (!global.performance) {
+		global.performance = {
+			now() {
+				const [sec, nsec] = process.hrtime();
+				return sec * 1000 + nsec / 1000000;
+			},
+		};
+	}
+
+	if (!global.TextEncoder) {
+		global.TextEncoder = require("util").TextEncoder;
+	}
+
+	if (!global.TextDecoder) {
+		global.TextDecoder = require("util").TextDecoder;
+	}
+
+	// End of polyfills for common API.
+
 	const encoder = new TextEncoder("utf-8");
 	const decoder = new TextDecoder("utf-8");
 
@@ -243,7 +265,15 @@
 						const id = this._nextCallbackTimeoutID;
 						this._nextCallbackTimeoutID++;
 						this._scheduledTimeouts.set(id, setTimeout(
-							() => { this._resume(); },
+							() => {
+								this._resume();
+								while (this._scheduledTimeouts.has(id)) {
+									// for some reason Go failed to register the timeout event, log and try again
+									// (temporary workaround for https://github.com/golang/go/issues/28975)
+									console.warn("scheduleTimeoutEvent: missed timeout event");
+									this._resume();
+								}
+							},
 							getInt64(sp + 8) + 1, // setTimeout has been seen to fire up to 1 millisecond early
 						));
 						mem().setInt32(sp + 16, id, true);
@@ -357,6 +387,34 @@
 						mem().setUint8(sp + 24, loadValue(sp + 8) instanceof loadValue(sp + 16));
 					},
 
+					// func copyBytesToGo(dst []byte, src ref) (int, bool)
+					"syscall/js.copyBytesToGo": (sp) => {
+						const dst = loadSlice(sp + 8);
+						const src = loadValue(sp + 32);
+						if (!(src instanceof Uint8Array)) {
+							mem().setUint8(sp + 48, 0);
+							return;
+						}
+						const toCopy = src.subarray(0, dst.length);
+						dst.set(toCopy);
+						setInt64(sp + 40, toCopy.length);
+						mem().setUint8(sp + 48, 1);
+					},
+
+					// func copyBytesToJS(dst ref, src []byte) (int, bool)
+					"syscall/js.copyBytesToJS": (sp) => {
+						const dst = loadValue(sp + 8);
+						const src = loadSlice(sp + 16);
+						if (!(dst instanceof Uint8Array)) {
+							mem().setUint8(sp + 48, 0);
+							return;
+						}
+						const toCopy = src.subarray(0, dst.length);
+						dst.set(toCopy);
+						setInt64(sp + 40, toCopy.length);
+						mem().setUint8(sp + 48, 1);
+					},
+
 					"debug": (value) => {
 						console.log(value);
 					},
@@ -373,7 +431,6 @@
 				true,
 				false,
 				global,
-				this._inst.exports.mem,
 				this,
 			];
 			this._refs = new Map();
@@ -385,9 +442,13 @@
 			let offset = 4096;
 
 			const strPtr = (str) => {
-				let ptr = offset;
-				new Uint8Array(mem.buffer, offset, str.length + 1).set(encoder.encode(str + "\0"));
-				offset += str.length + (8 - (str.length % 8));
+				const ptr = offset;
+				const bytes = encoder.encode(str + "\0");
+				new Uint8Array(mem.buffer, offset, bytes.length).set(bytes);
+				offset += bytes.length;
+				if (offset % 8 !== 0) {
+					offset += 8 - (offset % 8);
+				}
 				return ptr;
 			};
 
@@ -439,9 +500,15 @@
 		}
 	}
 
-	if (isNodeJS) {
+	if (
+		global.require &&
+		global.require.main === module &&
+		global.process &&
+		global.process.versions &&
+		!global.process.versions.electron
+	) {
 		if (process.argv.length < 3) {
-			process.stderr.write("usage: go_js_wasm_exec [wasm binary] [arguments]\n");
+			console.error("usage: go_js_wasm_exec [wasm binary] [arguments]");
 			process.exit(1);
 		}
 
@@ -459,7 +526,8 @@
 			});
 			return go.run(result.instance);
 		}).catch((err) => {
-			throw err;
+			console.error(err);
+			process.exit(1);
 		});
 	}
 })();