[jQuery] performance of jQuery.each

[Magnus O.]

Hi!

I saw that the jQuery.each function iterates over the array like this:

for ( name in object){}

>From what I read this is one of the slowest ways of iterating over an
array in js.

I made a very simple test like:

                                var array = [];
                                for (var i = 0; i < 1000000; i++)
                                        array[i] = Math.random();

                                var t = new Array();

//Start jquery.each test
                                var start = (new Date).getTime();
                                $(array).each(function() {
                                        t.push(this);
                                });
                                alert((new Date).getTime() - start);

                                t = new Array();

//Start another iteraton way test
                                start = (new Date).getTime();
                                var i = array.length;
                                while (i--) {
                                        t.push(array[i]);
                                }
                                alert((new Date).getTime() - start);



In my testbrowser the jquery.each testtime was 2378ms and the other
test was 110ms. This is a big difference. I know this test was very
easy bit it still shows that the each function could be made faster?

Is there any reason why the for ( name in object){} way of iterating
an array is used? Is this the most optimized way of iteration an
array?

//Magnus