.filter

filter li at even location

HTML

<ul>
  <li>list item 1</li>
  <li>list item 2</li>
  <li>list item 3</li>
  <li>list item 4</li>
</ul>
<button id='show-odd'>Show only odd li</button>
<button id='show-even'>Show only even li</button>

CSS

.highlighted {
  background : #3c763d;
}

JavaScript

$('#show-odd').on('click', function () {
		$('li').show();
		$('li').filter(function (index, element) {
    		$(element).toggle(index % 2 === 0);
        addClass = "highlighted"
    }).hide();
});

$('#show-even').on('click', function () {
		$('li').show();
		
    $('li').filter(function (index, element) {
    		$(element).toggle(index % 2 !== 0);
    }).hide();
});