Workers have "transferable" objects that in theory avoid copies, but still there's a world of difference between coarse-grained message-passing style, and fine-

Workers have "transferable" objects that in theory avoid copies, but still there's a world of difference between coarse-grained message-passing style, and fine-grained data parallelism you can get from something like rayon. JS "can" do a lot of things if you know how, and cleverly implement and optimize the code, but it's a Turing Tarpit. You wouldn't implement a video codec in JS. You could, but it's not the best language for it.