const res = fetch('https://api.github.com/orgs/facebook'); // yield here
Of course, fetch(), could yield a status specifying whether its calling-ancestors should yield, but this can become unwieldy very quickly, and might require an exception mechanism of its own. Better to just let called functions yield.
> But what if I want the fetch() function to decide whether to yield or not?
In javascript? The question doesn't really make sense, a function is either sync or async.
Well, either fetch() blocks, or not. If it blocks, then it should yield, its caller should yield, etc. If it doesn't block, then it can just run to completion.
> Well, either fetch() blocks, or not.
Javascript functions always block.
> If it blocks, then it should yield, its caller should yield, etc. If it doesn't block, then it can just run to completion.
If a function is async, you must yield[0]. It may not need* that capability (conditionally) and doesn't have to yield at all e.g.
function*() {
return 4;
}
[0] I think that's not an issue for async/await as it's syntactic sugar for then chains, the code itself may be converted to a generator or whatever but it will embed the driver
Call a generator function from a generator function? Sure, you just need to transitively yield its content using `yield* [[expr]]` (which delegates part of the iteration to the `expr` generator)