<script type="text/javascript">
            function getThreads()
            {
                if(jQuery("#blokat2")[0])
                {
                    document.getElementById('threads').className='bthreads2';
                }
                else
                {
                    document.getElementById('threads').className='bthreads1';
                }
            }    

            function getThreads2()
            {
                if(jQuery("#blokat")[0])
                {
                    document.getElementById('threads').className='bthreads2';
                }
                else
                {
                    document.getElementById('threads').className='bthreads1';
                }
            }
            
            function getPosts()
            {
                if(jQuery("#blokab")[0])
                {
                    document.getElementById('posts').className='bposts2';
                }
                else
                {
                    document.getElementById('posts').className='bposts1';
                }
            }    

            function getPosts2()
            {
                if(jQuery("#blokat2")[0])
                {
                    document.getElementById('posts').className='bposts2';
                }
                else
                {
                    document.getElementById('posts').className='bposts1';
                }
            }
        </script>

                        <a style="display: table-cell;font-size:12px;color:#fff;">
                            <div id="blokab" class="profilk_gg" onClick="document.getElementById('profil4').className='profil4_2'; document.getElementById('profile').className='profil4_4'; document.getElementById('posts').className='bposts2'; document.getElementById('blokab').className='profilk_gg blocka0'; document.getElementById('blokat').className='profilk_gg'; getThreads(); ">Posty</div>
                            <div id="blokat" class="blocka0" onClick="document.getElementById('profil4').className='profil4_1'; document.getElementById('profile').className='profil4_3'; document.getElementById('posts').className='bposts1'; document.getElementById('blokab').className='profilk_gg'; document.getElementById('blokat').className='profilk_gg blocka0'; getThreads2();">Posty</div
                        </a>

                        <a style="display: table-cell;font-size:12px;color:#fff;">
                            <div id="blokab2" class="profilk_gg" onClick="document.getElementById('profil4').className='profil4_2'; document.getElementById('profile').className='profil4_4'; document.getElementById('threads').className='bthreads2'; document.getElementById('blokab2').className='profilk_gg blocka0'; document.getElementById('blokat2').className='profilk_gg';getPosts();"> Tematy</div>
                            <div id="blokat2" class="blocka0" onClick="document.getElementById('profil4').className='profil4_1'; document.getElementById('profile').className='profil4_3'; document.getElementById('threads').className='bthreads1'; document.getElementById('blokab2').className='profilk_gg'; document.getElementById('blokat2').className='profilk_gg blocka0';getPosts2() "> Tematy</div>
                        </a>

Czy jest możliwość sprawdzenia czy istnieje dany div od np. id="blokat" oraz w tym samym divie klasa class="blocka0

[JAVASCRIPT] pobierz, plaintext 
if($('#blokat.blocka0').length > 0) console.log('istnieje');
[JAVASCRIPT] pobierz, plaintext