Worker subclass Example

examples/base/workerclass/coreworker.js

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+import { SimpleWorker  } from "simpleworker";
+
+/*
+ * coreworker.js
+ * Runs INSIDE the worker context. Uses global onmessage/postMessage.
+ * This is where you respond to main-thread messages.
+ */
+
+self.onmessage = SimpleWorker.prototype.onmessage.bind(self);

examples/base/workerclass/main.js

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+/*
+ * Copyright (c) 2016-2023  Moddable Tech, Inc.
+ *
+ *   This file is part of the Moddable SDK.
+ *
+ *   This work is licensed under the
+ *       Creative Commons Attribution 4.0 International License.
+ *   To view a copy of this license, visit
+ *       <http://creativecommons.org/licenses/by/4.0>.
+ *   or send a letter to Creative Commons, PO Box 1866,
+ *   Mountain View, CA 94042, USA.
+ *
+ */
+
+import { SimpleWorker } from "simpleworker";
+
+trace("main.js: hello\n");
+
+let index = 0
+
+function start() {
+	// note: chunk, heap (slots), and stack are very small - most real-world workers will require different settings
+	trace("main.js: Starting, creating worker\n");
+	const aWorker = new SimpleWorker("coreworker", {
+		static: 8 * 1024,		// total bytes for slots and chunks, in bytes
+		chunk: {				// size in bytes, for strings, array buffers
+			initial: 1536,
+			incremental: 256
+		},
+		heap: {					// in 16 byte slots
+			initial: 128,		// 2K bytes
+			incremental: 32
+		},
+		stack: 128				// number of 16 byte slots
+	});
+	trace("main.js: Worker created\n");
+	aWorker.postMessage({hello: "world", index: ++index});
+	aWorker.postMessage("hello, again");
+	aWorker.postMessage([1, 2, 3]);
+	trace("main.js: Messages sent\n");
+	aWorker.onmessage = function(message) {
+		trace(`main.js: worker -> ${JSON.stringify(message)}\n`);
+		if (3 === message.counter) {
+			trace(`main.js: restarting worker ${index}\n`);
+			aWorker.terminate();
+			start();
+		}
+	}
+}
+
+start();

examples/base/workerclass/manifest.json

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+{
+  "include": [
+		"$(MODDABLE)/examples/manifest_base.json",
+		"$(MODULES)/base/worker/manifest.json"
+	],
+  	"creation": {
+		"static": 12288,
+		"chunk": {
+			"initial": 1536,
+			"incremental": 512
+		},
+		"heap": {
+			"initial": 64,
+			"incremental": 32
+		},
+		"stack": 128,
+		"keys": {
+			"available": 32,
+			"name": 53,
+			"symbol": 3
+		},
+		"main": "main"
+	},
+  "modules": {
+    "*": [
+      "./main",
+      "./simpleworker",
+      "./coreworker"
+    ]
+  }
+}

examples/base/workerclass/simpleworker.js

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+/*
+ * SimpleWorker: main-thread wrapper that subclasses Worker.
+ * This class lives on the main side. The *worker-side* logic is in "coreworker.js".
+ */
+
+import Worker from "worker";
+
+export class SimpleWorker extends Worker {
+  static counter = 0;
+
+  onmessage(msg) {
+      trace(`simpleworker.js: counter: ${SimpleWorker.counter} message: ${JSON.stringify(msg)}\n`);
+      this.postMessage({hello: "from simple worker", counter: ++SimpleWorker.counter});
+  }
+}