Re:Why Would Anyone Need JavaScript Generator Functions?
by c-baby on Monday November 07, 2022 @08:00PM
(#33514721)
Hmm I see. So the value is in creating a kind of blocking promise. I can see how that might be useful in certain circumstances, but using blocking functionality isn't something you'd want to rely on in general.
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Re:Why Would Anyone Need JavaScript Generator Functions?
by qazxcvbnm on Tuesday November 08, 2022 @12:10AM
(#33516057)
No, the promise doesn't block, it just stays a promise. However, for synchronous calls, the Promise overhead is obviated.
In other words, the performance price of synchronous vs asynchronous calls is the price of a function call vs Promise implementation (i.e. event-loop machinery); the price of a function call, including the stack frame allocation, which is non-zero (recall the times that assembly programmers would dismiss languages like C as 'too-slow', having to allocate on function calls), versus pushing the Promise closure onto an event-loop, exiting the current event-loop, waiting for the next event-tick, popping off the next closure from the event stack, then creating the function call stack frame under a closure.
For inner-loops, the difference can be 20ms vs 20s.