[jQuery] Different jQuery.each(obj, callback) behaviour between arrays and objects
Why is it that the $.each utility method doesn't exit the loop on
return false when iterating over objects but does when iterating over
arrays? Here's a simple example that requires Firebug:
$.each([1,2,3], function() {
console.log('outer - ', arguments);
$.each([4,5], function() {
console.log('inner - ', arguments);
return false;
});
return false;
});
vs.
$.each({foo:'bar',baz:'quux'}, function() {
console.log('outer - ', arguments);
$.each({ichi:'ni',san:'shi'}, function() {
console.log('inner - ', arguments);
return false;
});
return false;
});
As you should see when iterating over objects return false has no
effect on the loop and console.log() is called 6 times (versus 2 when
iterating over arrays).
I know how this is happening as it's pretty clear in the the jQuery
code[1] but I'm now wondering why it's happening. Is it a bug in the
code, the documentation or some kind of arcane feature? Any
enlightenment on the matter would be most appreciated.
Cheers,
Dan
[1] It checks for the length property on the object it is about to
iterate over and if doesn't exist a plain "for in" loop is used,
otherwise an iterative loop is used which checks return value of the
callback and breaks from the loop if it is false.