AJAX Form Validation to see if course already exist always return true - ajax

Question

I want to validate my course name field if the course name inputted already exist using AJAX, but my ajax function always return the alert('Already exist') even if i inputted data that not yet in the database. Please help. Here is my code. Thanks.
View:
<script type="text/javascript">
var typingTimer;
var doneTypingInterval = 3000;
$('#course_name').keyup(function(){
typingTimer = setTimeout(check_course_name_exist, doneTypingInterval);
});
$('#course_name').keydown(function(){
clearTimeout(typingTimer);
});
function check_course_name_exist()
{
var course_name=$("#course_name").val();
var postData= {
'course_name':course_name
};
$.ajax({
type: "POST",
url: "<?php echo base_url();?>/courses/check_course_name_existence",
data: postData,
success: function(msg)
{
if(msg == 0)
{
alert('Already Exist!');
return false;
}
else
{
alert('Available');
return false;
}
return false;
}
});
$("html, body").animate({ scrollTop: 0 }, 600);
return false;
}
</script>
Controller:
function check_course_name_existence()
{
$course_name = $this->input->post('course_name');
$result = $this->course_booking_model->check_course_name_exist($course_name);
if ($result)
{
return true;
}
else
{
return false;
}
}
Model:
function check_course_name_exist($course_name)
{
$this->db->where("course_name",$course_name);
$query=$this->db->get("courses");
if($query->num_rows()>0)
{
return true;
}
else
{
return false;
}
}

Answer 1

You could use console.log() function from firebug. This way you will know exactly what the ajax returns. Example:
success: function(msg) {
console.log(msg);
}
This way you also know the type of the result variable.

Answer 2

jQuery, and Javascript generally, does not have access to the Boolean values that the PHP functions are returning. So either they return TRUE or FALSE does not make any difference for the JS part of your code.
You should try to echo something in your controller and then make your Javascript comparison based on that value.