disagree in every your point :)
1. if your variable name is "thing" in both cases, then you are talking
about the "thing", it is the same subject, so either your naming is wrong
or this is semantically correct to define it once.
2. your copy paste problem is can't be seriously considered.
1. Javascript has this bad part with globals and you should be very
carefull in general, doesn't matter if you copy pasted your code and
believes it is ok, its always good to read it again before use.
2. jslint has a globals check exactly for such cases.
3. my personal preference: it looks much more structured and consistent if
there are all declarations on the top. I can easier see all defined stuff
and easier detect if there is something unneeded or dublicate or can be
reused.
2011/1/15 And Clover <and-...@doxdesk.com>
> On Fri, 2011-01-14 at 10:12 -0800, cancel bubble wrote:
> > I understand that it's good practice to declare all your vars at the
> top of
> your function
>
> I disagree. This is one part of Crockford Dogma I think is badly
> mistaken. It's a habit from other languages that is, IMO, actively
> unhelpful in JS.
>
> function doSomething(things) {
> // Loop that does something
> for (var i= 0; i<things.length; i++) {
> var thing= things[i];
> thing.doPartOfSomething();
> }
>
> // Loop that does something else
> for (var i= 0; i<things.length; i++) {
> var thing= things[i];
> doAnotherPartOfSomething(thing);
> }
> }
>
> Here's two independent usages of the same variables `i` and `thing` in
> the same function. A purist might argue that you shouldn't reuse a
> variable in the same function, but in reality the alternatives are
> usually worse:
>
> - choosing different names each time means names have to be longer
> and/or less natural;
>
> - putting each independent or semi-independent block in its own function
> leads to an explosion of tiny unmanageable functions.
>
> So with the recommendation to move the `var` to the top:
>
> function doSomething(things) {
> var i, thing;
>
> // Loop that does something
> for (i= 0; i<things.length; i++) {
> thing= things[i];
> thing.doPartOfSomething();
> }
>
> // Loop that does something else
> for (i= 0; i<things.length; i++) {
> thing= things[i];
> doAnotherPartOfSomething(thing);
> }
> }
>
> But now there's a gap between declaration and usage, one that gets more
> impractical the longer the function gets. And there's unnecessary
> coupling between those previously-independent blocks. If during a
> refactoring, you cut-and-paste one of the loops out of `doSomething`
> into another function, you've got yourself an accidental global with all
> the problems that incurs.
>
> So, I'd say: don't move all `var` declarations to the top after all.
> Instead, declare `var` every time you first assign a variable, not
> don't care if it existed previously.
>
> --
> And Clover
> mailto:a...@doxdesk.com http://www.doxdesk.com
> skype:uknrbobince gtalk:chat?jid=bobi...@gmail.com
>
>
> --
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--
regards,
Oleg @oleg008
github.com/kof
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