Pass data to a Web Worker and transfer an ArrayBuffer efficiently

Tests whether you understand Web Worker data sharing and the cost of cloning versus zero-copy transfer. A strong answer covers that postMessage uses structured clone by default, duplicating data. For large ArrayBuffers, pass the buffer in the transfer list as the second argument; this moves the underlying memory to the worker, detaching it from the original so its byteLength becomes zero and access throws. Red flag: omitting the transfer list, confusing TypedArray serializability with transferability, or missing that the original loses access.