Unfortunately there's no way to remove the need for flushQueue being called with the browser's asynchronous scheduling mechanism (using setTimeout in your example) in the case where it isn't already flushing – that's the issue. Flushing the callback queue to completion is an optimization, not really a fix.
Yes, truly asynchronous things which took less than 5ms will now take at least 5ms to execute. But its a stretch to say that for Promises/A+ implementations
"... always require at least one more iteration of the event loop to resolve. This is not necessarily true of the standard callback approach."
as the article states. A fully synchronous chain of 20 operations wont take 100ms - it will only take 5ms
This is true in the scenario of a linear chain, e.g. `.then(foo).then(bar)`, but the spec also requires that the following should work (for interop purposes, among a few other scenarios):
So you might incur other harder-to-track-down penalties if you're doing interop between libraries somewhere, or if the promise chain has dependencies on the data provided by upstream resolvers.
If someOtherpromise is an already resolved promise from your own library, then it will still take just 5ms - the neat hack here is that asap will simply push another callback at the end of the queue (which is still being processed by the for loop) and the loop will simply get one more iteration straight in the middle of its execution.
If its from another library, then that other library may be using its own scheduler and you will loose those 5ms either way...
Yep. I believe the bigger promise libraries (bluebird et al) implement mechanisms similar to asap internally iirc.
My point was that violating the A+ spec instead of getting into the whole rabbit hole of timer clamps is not as unreasonable as one might think, and that doing so doesn't incur delays in any of those scenarios.
Maybe it isn't that unreasonable. But personally I do like guarantees, and in a stateful language I especially like guarantees about execution order.
If these guarantees can be offloaded to a library then thats really great, as I don't have to keep them in mind anymore, freeing my brain to think about the specific problem I'm trying to solve. One less thing to check for when debugging too.
There is also the bonus feature that stack overflows wont happen, which enables liberal use of recursive promise functions. (On the other hand, memory usage might still explode, so its not quite that easy... :D)
Those are good points. So far this approach hasn't been a problem w/ Mithril. If it turns out to be a bad idea down the road though, it can always be changed to conform w/ A+
I'm not really disputing the time anything will take, rather that "A+ doesn't require that you use the browser's asynchronous scheduling mechanism" – it very much does, even though that scheduling mechanism might be to occasionally flush your own managed event queue instead of handing every callback to the browser.
