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dbjdbj

jQuery.each()

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in Developing jQuery Core • 13 years ago

This was started almost a year ago. jQuery.each() improvement.

Inside it, instead of :

for ( name in object ) {

if ( callback.apply( object[ name ], args ) === false ) {

break;

}

One would expect to see :

for ( name in object ) {

if ( ! Object.prototype.hasOwnProperty.call( object, name )) continue ;

if ( callback.apply( object[ name ], args ) === false ) {

break;

}

Now this is somewhat controversial, beacuse we all know this will slow down this function. But it is perphaps inevitable, since it is "the right thing to do" ...

Can we plese have yes or no, with a reasoning behind?

Thank's:

--DBJ

Replies(5)

rkatic

Something like that would have sense if, and only if, there is intention to make jQuery immune on Object.prototype extending.
That would require huge (some relay hard) modifications on entire codebase.
I don't think that it is worthwhile, since Object.prototype extending is de facto considered wrong for many reasons.

dbjdbj

Re: Re: jQuery.each()

13 years ago

Do we really have to have a debate around this simple issue?

Can you please not get offended if I ask you to google (for example) : "Crockford hasOwnProperty" ...

--DBJ

jeresig

Re: Re: jQuery.each()

13 years ago

"I don't think that it is worthwhile, since Object.prototype extending is de facto considered wrong for many reasons."

I agree completely. There are already a few bad cases that jQuery doesn't handle: We don't support malformed markup, we don't support pages in quirks mode, we don't support people extending Object.prototype.

So that being said, there are two cases here:

1) Someone extending Object.prototype (in this case we would need to fix every internal use of for..in in jQuery).

2) Making some of the looping methods immune to cases where another prototype has been extended. For example:

var Foo = function(){};
Foo.prototype.test = "test";
var obj = new Foo();
jQuery.each( obj, function(){} ); // Probably shouldn't loop

Same goes with the post that was made concerning isEmptyObject. I can try and look in to these for 1.4.3.

dbjdbj

Re: jQuery.each()

13 years ago

@John, In both cases (each() and isEmptyObject() ) we all will be inevitably coming to "javascript theological discussion" , revolving around "should we loop , should we not loop, or must we loop", etc ...as commented on the last line of the snippet above. I personally think this unproductive "discusion" should be avoided and we should let caller decide. And, the default behaviour should be not to iterate over "things" which are up the prototype chain ...

jQuery.each = function ( object, callback, look_up_the_prototype_chain )

{

look_up_the_prototype_chain = look_up_the_prototype_chain || false ;

// etc ...

}

I think, 1.4.3 is indeed a very good opportunity to implement this.

--DBJ

PS: Less important stuff : "...2) Making some of the looping methods immune to cases where another prototype has been extended. ..."

This is exactly where I am coming from. The only reason why each() should/could be looked into.

I thought it is "obvious" but it seems it is not: I too do *not* think that jQuery should be supporting Object.prototype abuse ... As I have written many times before.

rkatic

Re: jQuery.each()

13 years ago

Is it common to iterate a not plain object?

However, if needed, I would suggest a $.eachProperty() that would enumerate properties even if there is a "length" property (http://gist.github.com/306155), and leaving $.each() as is for beck compatibility, and eventually deprecating $.each( {...}, function(){...} ).

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