Question

I have these elements, and I need to select the li inside the ul where opacity=1.
How can I do this?

<ul class="class" id="ul">
                <li style="width: 100%; list-style: none outside none; position: absolute; top: 0px; left: 0px; z-index: 98; opacity: 0;"><a title="title1" href=""><img alt="alt" class="class_name" src="/images/7dfc294d5c3bcebecb2ec0e44fd27d1c.jpg"></a></li>
                <li style="width: 100%; list-style: none outside none; position: absolute; top: 0px; left: 0px; z-index: 98; opacity: 0;"><a title="title2" href=""><img alt="alt" class="class_name " src="/images/a9c9eb42934df4576b352d88f607f292.jpg"></a></li>
                <li style="width: 100%; list-style: none outside none; position: absolute; top: 0px; left: 0px; z-index: 98; opacity: 0;"><a title="title3" href=""><img alt="alt" class="class_name " src="/images/b64264692c0d648068c9d1380e9099c1.jpg"></a></li>
                <li style="width: 100%; list-style: none outside none; position: absolute; top: 0px; left: 0px; z-index: 99; opacity: 1;"><a title="title4" href=""><img alt="alt" class="class_name " src="/images/43e3e5e2edc4234ecddbc89636e4e224.jpg"></a></li>
                <li style="width: 100%; list-style: none outside none; position: absolute; top: 0px; left: 0px; z-index: 98; opacity: 0;"><a title="title5" href=""><img alt="e-alt" class="class_name " src="/images/31a156ce7f7ab5485366d24f6cbfbede.jpg"></a></li>
            </ul>

Answer 1

$('#ul li').filter(function() {
  return $(this).css('opacity') == '1';
});

DEMO

You can also try with .each()

var lis = [];
$('#ul li').each(function() {
    if ($(this).css('opacity') == '1') {
        lis.push(this);
    }
});

DEMO

or using .map()

var lis = $('#ul li').map(function() {
    if($(this).css('opacity') == '1')
        return this;
}).get();

DEMO