Combining jQuery :not and :nth-child selectors

Question

$j(\'.select-all-these:not(.except-these):nth-child(3n)\');

I\'m trying to select every third item that doesn\'t have a particular class. This is m

Answer 1

The only way I could see to make this work was to use two filter() calls:

$('.select').filter(
    function(){
        return !$(this).hasClass('dontselect');
    }).filter(
        function(i){
            return (i+1)%3 == 0; // unless you want a zero-based count, regular CSS is one-based
        }).css('color','red');

JS Fiddle demo.

You could, though, use a single filter() call, with an external variable:

var count = 0;
$('.select').filter(
    function(){
        console.log(!$(this).hasClass('dontselect'));
        if (!$(this).hasClass('dontselect')){
            count++;
            return count%3 == 0;
        }
    }).css('color','red');

JS Fiddle demo.

JS Perf reports that the single filter is, unsurprisingly, a little faster, but only very, very, very marginally.

References:

• filter().
• hasClass().