[jQuery] how to disable and enable submit button via jQuery [code included]

[jQuery] how to disable and enable submit button via jQuery [code included]


        if($("#answer").val().length < 200){
         $("#submitanswer").attr("disabled","disabled");
         }
will disable it but than upon the key press I want to enable it and
this doesnt work:
$("#answer").keyup(
            function(){
                $('#answer'+'count').text('Count: '+ $("#answer").val().length);
                if( $("#answer").val().length > 200 ){
                alert('ere');
                     $("submitanswer").removeAttr("disabled");
                }
            }
        );
how can you help?