如何不在ajax提交codeigniter上重定向页面

So, i have a following ajax code and controller code, my problem is i want to insert comment withouth refreshing the page and not redirecting to another page, and it seems that whenever i hit btnCommentSubmit it is redirecting me to my controller page, how to prevent that?
Ps. The insertion is working
//AJAX CODE

$('#btnComment').click(function(e){

            var comment_identifier = $(this).data("value");
            var comment_by = $(this).data("id");
            $('#formAddComment').attr('action', '<?php echo base_url() ?>Discussion/addComment/'+comment_identifier+"/"+comment_by);
        });

        $('#btnCommentSubmit').click(function(){
            var url = $('#formAddComment').attr('action');
            var addCommentTxt = $('#addCommentTxt').val();
            $.ajax({
                type: 'post',
                url: url,
                data: {addCommentTxt:addCommentTxt},
                success: function(){
                    alert('success');
                },
                error: function(){
                    console.log(data);
                    alert('Could not add data');
                }
            });

        });
    });

//Controller code

public function addComment(){
        $cIden = $this->uri->segment(3);
        $cBy = $this->uri->segment(4);
        $data = array(
            "comment_identifier" => $cIden,
            "comment_by" => preg_replace('/[^a-zA-Z-]/', ' ', $cBy),
            "comment" => $this->input->post('addCommentTxt'),
            "comment_at" => time() 
        );  

        if ($this->Crud_model->insert('comments',$data)) {
            return true;
        }else{
            return false;
        }

    }

Add e.preventDefault() in the beginning of your function:

$('#btnCommentSubmit').click(function(e){
  e.preventDefault();
  ...

}

You may want to use jQuery form plugin. It submit form to our controller without any page refresh/redirect. I use it all the time.

https://jquery-form.github.io/form/

Example usage:

    $('#form').ajaxForm({
        beforeSubmit: function() {
            //just optional confirmation
            if (!confirm('Are you sure want to submit this comment?')) return false;
            show_loading();
        },
        success: function(status) {
            hide_loading();
            if (status == true) {
                alert('success');
            } else {
                alert('Could not add data');
            }
        }
    });

You can use javascript:void(0); like href="javascript:void(0);"