<div>
    <p class="foo">Something_1</p>
    <p class="bizz foo">Something_2</p>
    <p class="foo bizz">Something_3</p>
</div>
<script>
    $('div').has('p').css('color','red');
    $('p').is('.foo').css('color','green');
    $('p').last().css('color','blue');
</script>