Ok, MDC specs do not consider the length, so the most close is this
Array.forEach = Array.forEach || function(obj, callback, scope){
for(var i = 0, length = obj.length; i < length; ++i){
if(i in obj) callback.call(scope, obj[i], i,
obj);
};
};
Sorry for that :D
2009/5/22 Andrea Giammarchi <[email protected]>
> To be honest I wrote something a bit redundant, this one is better if you
> want to use the length.
>
> Array.forEach = Array.forEach || function(obj, callback, scope){
> for(var i = 0; i < obj.length; ++i){
> if(i in obj)
> callback.call(scope, obj[i], i, obj);
> };
> };
> even more simple, isn't it?
>
> The scenario with DOM is tipically this one
>
> div
> div
> div
> div
> div
>
> getElementsByTagName("div") will have length 5, let's say the first one,
> the outer div, match something we were looking for and we remove it. With
> above version of Array.forEach the loop will be instantly stopped at next i
> < obj.length, because it changed, while with cached length, not updated, the
> loop will go on other 4 times and the i in obj will always fail. I guess
> then this version is, generally speacking, faster.
>
> I am going to investigate a bit more about FireFox native behaviour though.
>
> Regards
>
>
> 2009/5/22 Andrea Giammarchi <[email protected]>
>
> Actually, the main usage of Array.forEach is with non Array, like live
>> objects. Since with DOM is easy to remove a node and the result of the live
>> object could be completely changed, do you prefere 100 useless if I in obj
>> or just a loop brek thanks to changed length? Dunno which is faster and the
>> performance problem is the if, necessary if you want specs like, not the
>> length. Regards
>>
>> On May 22, 2009 1:05 AM, "Robert Katić" <[email protected]> wrote:
>>
>>
>> There is no need to take in consideration eventual length updates;
>> that slows considerably, and it is not garanted in any/each native
>> implementation:
>>
>>
>> https://developer.mozilla.org/En/Core_JavaScript_1.5_Reference/Global_Objects/Array/ForEach
>>
>> On May 21, 5:39 pm, Andrea Giammarchi <[email protected]>
>> wrote:
>>
>> > IE8? obviously no, how can you pretend a browser that implemented >
>> defineProperty only for Window...
>>
>> > On Thu, May 21, 2009 at 4:11 PM, diogobaeder <[email protected]>
>> wrote: > > > Hmmm... close, I...
>>
>>
>
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