Hi, i have some problem, how do i compare the data returned by ajax ?

Code:
   $.ajax{(
     type:'post',
     url: 'some.php',
     success: function(data){
        if(data=='ok')
           {
               alert('you are ok');
         }
       else if(data=='sad'){
             alert('you are sad');
      }
        else if(data=='mad')
           {
            alert('you are mad');
      }
    }
)};
million thanks in advance.