> I often see people using fancy library methods, like Prototype's
> Enumerable.each(), to
> loop over arrays.

> What's the point of this? Why not just do a standard for loop, like
> so:

> for ( var i = 0; i < myArray.length; i++ ) {
>    // ...
> }

> It seems like it'd be faster, since it's working closer to the bare
> metal. Am I wrong about this, or is there some other nuance I'm
> missing?

> In some cases, yes, you may notice a speed difference. But only if you're
> looping through a megaton of items and doing a supermegaton of processing.

> In most case, it's effect on performance is not worth mentioning.

> The main point of it, though, is it's a nice clean way to iterate a
> collection AND have a new local scope for each iteration of the loop. The
> closure provided by .each(fn(item, index)) comes in very handy in many
> cases.

> Plus:

> for (var i = 0; i < blah.length; i++) {
> var item = blah[i];
> doSomething(item);

> }

> is more verbose than:

> blah.each(doSomething);

> And finally, you're right that .each is one of the lesser value-add methods
> in Enumerable. Certainly .invoke, .collect, etc... are doing more work. But
> personally I like the "predicate and delegate" patterns - also prevalent in
> C# and Java (via Generics) - that Enumerable provides with it methods,
> including each.

> I've been bitten several times with a for loop that didn't quite work as
> expected because I, or someone, forgot about the absence of block level
> scoping in javascript.

> On Mon, Jun 30, 2008 at 7:10 PM, greenie2600 <greenie2...@yahoo.com> wrote:

> > I often see people using fancy library methods, like Prototype's
> > Enumerable.each(), to
> > loop over arrays.

> > What's the point of this? Why not just do a standard for loop, like
> > so:

> > for ( var i = 0; i < myArray.length; i++ ) {
> >    // ...
> > }

> > It seems like it'd be faster, since it's working closer to the bare
> > metal. Am I wrong about this, or is there some other nuance I'm
> > missing?

> --
> Ryan Gahl
> Manager, Senior Software Engineer
> Nth Penguin, LLChttp://www.nthpenguin.com
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> Ah. The bit about creating a clean scope for each iteration makes
> sense. I've been simulating that by resetting my "block-level"
> variables to null at the top of the loop.

> Thanks! I'll keep this in mind.