About parsererror SyntaxError: Unexpected end of input (CI with Jquery&ajax ) -

i don't understand error .

i use codeigneter , jquery&ajax

error parsererror

personedit.php

$(document).ready(function(){     var options = {         datatype :      'json',         beforesubmit:   saveshowrequest, // pre-submit callback         success:        saveshowresponse,  //post-submit callback         error: function (xhr, ajaxoptions, thrownerror){             //alert('error !!'++ xhr.statustext);              //alert(thrownerror);             $('#output_test').html('<h2>error !!!!: ' + xhr.statustext +'</h2>'+thrownerror );         }           // other available options:          //url:       url         // override form's 'action' attribute         //type:      type        // 'get' or 'post', override form's 'method' attribute          //datatype:  null        // 'xml', 'script', or 'json' (expected server response type)          //clearform: true        // clear form fields after successful submit          //resetform: true        // reset form after successful submit          //$.ajax options can used here too, example:          //timeout:   3000   };          $('#myeditpersonform').ajaxform(options);   });   // pre-submit callback  function saveshowrequest(formdata, jqform, options) {      // formdata array; here use $.param convert string display      // form plugin automatically when submits data      var querystring = $.param(formdata);       // jqform jquery object encapsulating form element.  access      // dom element form this:      // var formelement = jqform[0];       alert('about submit: \n\n' + querystring);       // here return false prevent form being submitted;      // returning other false allow form submit continue      return true;  }   // post-submit callback  function saveshowresponse()  {       // if ajaxform method passed options object datatype      // property set 'json' first argument success callback      // json data object returned server                      //alert display     alert('success exemple return respone');       //html display     $('#output_test').html('success exemple return respone '); }  

ajax_post.php // ci

function update_person(){     // set common properties                   // run validation          // save data         $id = $this->input->post('id');         $person = array('name' =$this->input->post('name'),                         'gender' =$this->input->post('gender'),                         'dob' =date('y-m-d', strtotime($this->input->post('dob'))));         $this->personmodel->update($id,$person);          // set user message         $data['message'] = '<div class="success">update person success</div>';       } 

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$('#output_test').html('<h2>error !!!!: ' + xhr.statustext +'</h2>'+thrownerror); alert(xhr.responsetext); 

alert(xht.responsetext); ok . can send responsetext (no error)

and why cannot use success: saveshowresponse,

this error means response coming url not json, there's error attempting parse such.

either in network panel (easier), or adjust error handler see response server returning, looking @ responsetext this:

$('#output_test').html('<h2>error !!!!: ' + xhr.statustext +'</h2>'+thrownerror); alert(xhr.responsetext);