All the workers that we've created so far in this chapter—dedicated workers and shared workers—were launched by the main thread. In this section, we'll address the idea of sub-workers. They're similar to dedicated workers, only with a different creator. For example, a sub-worker can't directly interact with the main thread, only by proxy through the thread that spawned the sub-worker.
We'll look at dividing larger tasks into smaller ones, and we'll also look at some challenges surrounding sub-workers.
The job of our web workers is to carry out tasks in such a way that the main thread can continue to service things, such as DOM events, without interruption. Some tasks are straightforward for a web worker thread to handle. They take input, compute a result, and return that result as output. But, what if the task is larger? What if it involves a number of smaller discrete steps, allowing us to breakdown the larger task into smaller...