In some cases, yes, it's pure sugar.
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 <[EMAIL PROTECTED]> 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?
>
> >
>
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Ryan Gahl
Manager, Senior Software Engineer
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http://www.nthpenguin.com
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