Sharing a TypedArray view of a SharedArrayBuffer with a worker - is the full SharedArrayBuffer accessible?

Question

If I create a SharedArrayBuffer, and then create a 'view' of said buffer via a TypedArray, and then send that TypedArray to a Worker via postMessage, is the worker able to access the full data of the TypedArray?

Answer 1

Yes, the full underlying buffer is shared with the web worker:

<!-- test.html -->
<script>
  // Main thread
  const sharedBuffer = new SharedArrayBuffer(100); 
  const fullBuffer = new Uint8Array(sharedBuffer);
  fullBuffer.set([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]); // Fill the start of the buffer with some data
  const partOfBuffer = new Uint8Array(sharedBuffer, 5); // Create a view that leaves off the first few numbers

  const worker = new Worker('worker.js');
  worker.postMessage(partOfBuffer);
</script>

// worker.js
onmessage = function(e) {
  const partOfBuffer = e.data;
  console.log(new Uint8Array(partOfBuffer.buffer)); // logs the full buffer data - i.e. including the first few numbers
}