if(isset($_POST)){
    $data = array(); 
    $gel = $db->prepare("SELECT icerik FROM tablo ");
    $gel->execute(); 
    while ($gelsin = $gel->fetch(2)) { 
        $data[] =  array(
            'icerik' => $gelsin['icerik'] 
        ); 
    }
    echo json_encode($data);  
}

$(document).ready(function(){  
    $.ajax({
        url: "post.php",  
        type:'POST',  
        dataType: 'json',
        data:"duyuru", 
        success:function(response){  
            ityped.init('.ityped', {
                // strings: [response.icerik],
                strings: response.icerik,
                loop: true,
                typeSpeed: 50,
                backSpeed: 20,
                startDelay: 250,
                backDelay: 2000 
            })
             
        }
    }); 
});