Both methods appear to produce the same results, but I've been hard-pressed to actually convince people that the second method works, since it's apparently not commonly known.
// Create some data
var foo = { 'vals':[ {'id':'foo'}, {'id':'bar'} ] };
// Common Method
$.each(foo.vals, function(i,o){
alert(this.id);
});
// Alternative (lesser-known?) Method
$(foo.vals).each(function(i,o){
alert(this.id);
});
Upon checking the source, these two appear to be one-in-the-same. The second method follows:
each: function( callback, args ) {
return jQuery.each( this, callback, args );
}
This method demonstrably calls the more commonly-known method, meaning it's just as legitimate. Is this understanding correct, or am I missing something here?
I have typically trusted this method since it didn't cause me to deviate from standard practices with regards to selectors. Let's face it, we're trained to do:
$("p").each();
So it seems only natural to do:
$(obj).each();
Am I mistaken?
The difference between the two is actually exponential depending on how you are using it.
The first $.each
constitutes a single function call to start the iterator.
The second $(foo.vals).each
makes three function calls to start the iterator. The first is to the $()
which produces a new jQuery wrapper set (Not sure how many other function calls are made during this process). Then the call to $().each
. And finally it makes the internal call to jQuery.each
to start the iterator.
In your example, the difference would be negligible to say the least. However, in a nested use scenario, you might find performance becoming an issue.
Finally, Cody Lindley in jQuery Enlightenment does not recommend using $.each
for iterations greater than 1000 because of the function calls involved. Use a normal for( var i = 0...
loop.
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