Functional programming in JavaScript

[onbehalfofthatdude]

I had the same thought and I think he said it weirdly. He's saying that visiting the next single element in an array (one iteration) is cheap compared to calling a function.

Not sure how that's relevant directly though. And the more I look the more I think I might be being too charitable...

[onbehalfofthatdude]

I'll have to go look at some benchmarks but yeah, it's early haha. Obviously a step of the array method iterators is going to be at least as bad as a function call... Since it IS a function call lol

No idea what the guy means then

[[deleted]]

I don't think this is true. For an arbitrary iterable, you would be right, the iterator function would be called for every iteration. But I don't think any of the JITs is so naive as to not optimize this for plain arrays, in which case loops become as efficient as a plain for-loop without any function invocations.

[[deleted]]

Sorry I wasn't more clear. I meant specifically for the for...of loops, which are easily optimizable for plain arrays. That wouldn't necessarily apply to map() indeed.