Execute controller from view

[eluser]Unknown[/eluser]
I m doing

$.ajax({
async: false,
url:'<?php echo base_url('user/demo/sample_foo'); ?>',
dataType: 'json',
success: function(result){
if(result == true)
alert("random text");
else
alert("some_other_random_text");
}
});

In demo controller function sample_foo returns true or false values only, but when i alert it shows "[object,object]"
What can i do to retrive true and false value ?