How to The selected TR and TD Values in Javascript

How to The selected TR and TD Values in Javascript?

$("#table tr").click(function(){
   $(this).addClass('selected').siblings().removeClass('selected');    
   var value=$(this).find('td:first').html();
   alert(value);    
});

$('.ok').on('click', function(e){
    alert($("#table tr.selected td:first").html());
});