html - form getting redirected to base_url when action is set to null in codeigniter view -


i submit below form processing code in controller after processing redirecting base url. haven't used redirect in controller function. why redirecting base_url when action null?

this form code

<form action="" class="form-horizontal contact-1"  role="form" method="post" id="contactform">         <input type="hidden" name="operation" value="newquery">             <div class="form-group">             <div class="col-sm-6">             <input type="text" class="form-control"  name="name" id="name" placeholder="name">             </div>             <div class="col-sm-6">             <input type="text"  class="form-control" name="email" id="email" placeholder="email">             </div>             </div>             <div class="form-group">               <div class="col-sm-12">               <input class="form-control" id="subject" type="text" name="subject" placeholder="subject">               <textarea name="message" type="text" id="msg" class="form-control textarea" cols="30" rows="5" placeholder="message"></textarea>               <button type="submit" id="contsub" class="btn btn-primary btn-block contact-1-button"   data-loading-text="sending" ><i class="fa  fa-send"></i>  send message</button>              </div>             </div> </form> 

and ajax call

    <script>             $(document).ready(function() {                 $("#contsub").click(function() {                     var name = $("#name").val();                     var email = $("#email").val();                     var subject = $("#subject").val();                     var msg = $("#msg").val();                     if (name == '' || email == '' || subject == '' || msg == '') {                      } else {                         // returns successful data submission message when entered information stored in database.                         $.post("contactform.php", {                             name: name,                             email: email,                             subject: contact,                             msg: msg                         }, function(data) {                             alert(data);                             $('#form')[0].reset(); // reset form fields                         });                     }                 });             });         </script> 

i not able figure out problem is?

1.if set form action empty, form submitted current url.so @ browser current url , think same base_url.
2.if click on contsub button javascript $("#contsub").click(function() not execute because when click button submit form , redirect action url.change <button type="submit" <button type="button" not submit form , javascript work.