ladybird/Tests/LibWeb/Text/input/Worker/Worker-postMessage-transfer.html

<script src="../include.js"></script>
<script>
    asyncTest((done) => {
        const workerScript = `
            self.onmessage = function(evt) {
                const receivedBuffer = evt.data;
                self.postMessage(receivedBuffer, [receivedBuffer]);
            };
        `;

        const blob = new Blob([workerScript], { type: 'application/javascript' });
        const workerScriptURL = URL.createObjectURL(blob);
        const worker = new Worker(workerScriptURL);

        worker.onmessage = function(evt) {
            const bufTransferredBackFromWorker = evt.data;
            const decoder = new TextDecoder();

            println('Message received from worker: ' + decoder.decode(bufTransferredBackFromWorker));
            done();
        };

        const encoder = new TextEncoder();
        const message = encoder.encode("Hello, world");
        const myBuf = message.buffer;

        worker.postMessage(myBuf, [myBuf]);
    });
</script>