On Sep 26, 7:53*pm, Thomas 'PointedEars' Lahn <PointedE...@web.de>
wrote:
> Jorge wrote:
> > SAM wrote:
> >> for(i in lista) { }
>
> > Hmm, what a lovely 'for..in' !
> > I had never applied it to an array.
>
> > javascript:a=['0',,,,,,,,'8'], a[4]= '4', n= 0;for (i in a) { n++;
> > alert(i+a[i]); };alert(n+' !== '+a.length);
>
> > Is it predictable in this case ? the order of 'i', I mean ?
>
> No; read ES3F, 12.6.4.
>

That's what I thought, but as SAM said, however hard I try, it always
shows them in the right order.

--
Jorge.

On Sep 26, 2:38*pm, SAM <stephanemoriaux.NoAd...@wanadoo.fr.invalid>
wrote:
> Le 9/25/08 7:14 PM, Jorge a écrit :
>
> > On Sep 24, 1:48 am, SAM <stephanemoriaux.NoAd...@wanadoo.fr.invalid>
> > wrote:
> >> for(i in lista) { }
>
> > Hmm, what a lovely 'for..in' !
> > I had never applied it to an array.
>
> > javascript:a=['0',,,,,,,,'8'], a[4]= '4', n= 0;for (i in a) { n++;
> > alert(i+a[i]); };alert(n+' !== '+a.length);
>
> > Is it predictable in this case ? the order of 'i', I mean ?
>
> What do you mean by 'predictable' ?
>

That the sequence grows orderly. But the spec states that properties
might show up in any order. (See Thomas' ('Mr. spec') post...)

--
Jorge.

On 2008-09-27 01:56, Jorge wrote:
> On Sep 26, 7:53 pm, Thomas 'PointedEars' Lahn <PointedE...@web.de>
...
>> > javascript:a=['0',,,,,,,,'8'], a[4]= '4', n= 0;for (i in a) { n++;
>> > alert(i+a[i]); };alert(n+' !== '+a.length);
>>
>> > Is it predictable in this case ? the order of 'i', I mean ?
>>
>> No; read ES3F, 12.6.4.
>>
>
> That's what I thought, but as SAM said, however hard I try, it always
> shows them in the right order.

For one thing, there's this possibility:

var a = ['0', '1'];
a.blah = "ho hum";
a.push('2', '3');
for (var i in a) {
document.write(i + ": " + a[i] + "<br>");
}

Now I'm afraid I'll have to partly contradict what I wrote earlier in a
different thread (alert vs. window.alert). In this specific case, I
would *not* trust implementations to always return the results in the
expected order, even though empirical evidence suggests that they
currently do. The reason why I'm more reluctant here is that we're
always warned (and that goes for various different programming
languages) that hashes / associative arrays / objects should not be
trusted to return their keys in any particular order when you iterate
like that. This is a very common pitfall in many languages. Some do have
ordered hashes (like the [weird] PHP arrays, which are actually a mix of
arrays and hashes, or Perl's pseudohashes), but I'll bet my hat that
Thomas can come up with a passage in the ECMAScript specs that says that
object properties aren't guaranteed to be returned in any particular
order in a for..in loop.

In short, it may work. I can even imagine that the current script
engines are designed to work that way, because too many badly written
scripts would fail otherwise. But I wouldn't trust it. Iterate over an
array like an array, and an object like an object.


- Conrad

On Sep 26, 2:38*pm, SAM <stephanemoriaux.NoAd...@wanadoo.fr.invalid>
wrote:
> Le 9/25/08 7:14 PM, Jorge a écrit :
>
> > On Sep 24, 1:48 am, SAM <stephanemoriaux.NoAd...@wanadoo.fr.invalid>
> > wrote:
> >> for(i in lista) { }
>
> > Hmm, what a lovely 'for..in' !
> > I had never applied it to an array.
>
> > javascript:a=['0',,,,,,,,'8'], a[4]= '4', n= 0;for (i in a) { n++;
> > alert(i+a[i]); };alert(n+' !== '+a.length);
>
> > Is it predictable in this case ? the order of 'i', I mean ?
>
> What do you mean by 'predictable' ?
>
> javascript:a=['0',,,,,,,,'8'], a[4]= '4';for(i in a)
> if(a[i])alert('elem.t #'+i+' = '+a[i]);
>

When I run this in webkit r36882 the last (4th) alert reads:

'elem.t #peek = function () {return this[this.length-1]}' ???

What (the hell) is that ??

--
Jorge.

On Sep 27, 2:26*am, Conrad Lender <crlen...@yahoo.com> wrote:
> On 2008-09-27 01:56, Jorge wrote:
>
> > On Sep 26, 7:53 pm, Thomas 'PointedEars' Lahn <PointedE...@web.de>
> ..
> >> > javascript:a=['0',,,,,,,,'8'], a[4]= '4', n= 0;for (i in a) { n++;
> >> > alert(i+a[i]); };alert(n+' !== '+a.length);
>
> >> > Is it predictable in this case ? the order of 'i', I mean ?
>
> >> No; read ES3F, 12.6.4.
>
> > That's what I thought, but as SAM said, however hard I try, it always
> > shows them in the right order.
>
> For one thing, there's this possibility:
>
> var a = ['0', '1'];
> a.blah = "ho hum";
> a.push('2', '3');
> for (var i in a) {
> * * document.write(i + ": " + a[i] + "<br>");
>
> }
>

Yes, but still sorts it well.
This one instead... :-(

javascript:a=[0,,2];a[1]=undefined;for (i in a) { alert(i+':'+a[i]) };

--
Jorge.

On 2008-09-27 03:04, Jorge wrote:
>> var a = ['0', '1'];
>> a.blah = "ho hum";
>> a.push('2', '3');
>> for (var i in a) {
>> document.write(i + ": " + a[i] + "<br>");
>>
>> }
>
> Yes, but still sorts it well.

For custom values of "well".
It sorts "blah" between index 1 and 2 (FF2).

> This one instead... :-(
>
> javascript:a=[0,,2];a[1]=undefined;for (i in a) { alert(i+':'+a[i]) };

I don't get it. What does this display in your browser?
All it does in FF2 is alert:

0:0
1:undefined
2:2

Which is what you would expect, I guess.


- Conrad

On Sep 27, 3:55*am, Conrad Lender <crlen...@yahoo.com> wrote:
> On 2008-09-27 03:04, Jorge wrote:
>
> >> var a = ['0', '1'];
> >> a.blah = "ho hum";
> >> a.push('2', '3');
> >> for (var i in a) {
> >> * * document.write(i + ": " + a[i] + "<br>");
>
> >> }
>
> > Yes, but still sorts it well.
>
> For custom values of "well".
> It sorts "blah" between index 1 and 2 (FF2).

Ah, :-( then.

> > This one instead... :-(
>
> > javascript:a=[0,,2];a[1]=undefined;for (i in a) { alert(i+':'+a[i])};
>
> I don't get it. What does this display in your browser?
> All it does in FF2 is alert:
>
> * 0:0
> * 1:undefined
> * 2:2
>
> Which is what you would expect, I guess.
>

No, see, here a[1] === undefined as well, but it's not listed :

javascript:a= [0,,2];for (i in a) { alert(i+':'+a[i]) };

I was thinking that the for..in would help in transversing a sparse
array (an array with 'holes'), but that's not the case.

--
Jorge.