alt Hacker NewsI would imagine browsers optimize the iterator protocol away for arrays. At least on https://jsben.ch/iJFZ4 for..of is a smidge faster than an old-school loop.
I would imagine browsers optimize the iterator protocol away for arrays. At least on https://jsben.ch/iJFZ4 for..of is a smidge faster than an old-school loop.
You accidentally included the array initialization in the benchmarked code ("setup block" vs "boilerplate block"), dwarfing everything else. If we're talking about an already allocated array the difference is pretty big:
https://jsben.ch/FgDA6
… but in a way you're correct that this is rarely the actual bottleneck in the surrounding code. Still, "death by a thousand papercuts" and all that. Plus having old-school for-loops as a habit makes it easier to spot the true botllenecks.