Calling Controller method from javascript using CodeIgniter

I am using CodeIgniter ..I can’t access the method from the controller

I have this script in my view

<script>
  function showHint(str){
    if (str.length==0){ 
        document.getElementById("txtHint").innerHTML="";
        return;
    }
    var xmlhttp=new XMLHttpRequest();
    xmlhttp.onreadystatechange=function(){
        if (xmlhttp.readyState==4 && xmlhttp.status==200){
               document.getElementById("txtHint").innerHTML=xmlhttp.responseText;
         }
    }
    xmlhttp.open("GET","ajax/ajaxSearch",true);
    xmlhttp.send();
  }
  </script>

and i have a controller named ajax with a method ajaxSearch()

public function ajaxSearch(){
    echo "received";
}

Folder Structure

htdocs/
     AjaxTry/
        AjaxSearchingMVC/
            application/
                controller/
                    ajax.php                //controller
                          ajaxSearch()      //method
                views/
                    view_ajax.php           // here is where the script is written

What could be the possible problem here?

Answer

Do the following…

In controller create example.php and leave ajax.php like it is. And in views leave like you have already view_ajax.php

We are going to load data from example.php with Ajax

Your ajax.php should look like this

class ajax extends CI_Controller {

    public function index()
    {
        $this->load->helper('url'); // if you are going to use helpher don't forget to load it ( of course if you are not loading it by default )
        $this->load->view('view_ajax.php'); // in `view_ajax.php` you must have JavaScript code
    }
}

JavaScript code for testing purpose write like

<script>
var xmlhttp=new XMLHttpRequest();
    xmlhttp.onreadystatechange=function(){
        if (xmlhttp.readyState==4 && xmlhttp.status==200){
               alert(xmlhttp.responseText);
               console.log(xmlhttp.responseText);// you will see OKKK in console
         }
    }
xmlhttp.open("GET","../index.php/example",true); // first try `../index.php/example` ( extension depends if you enable/disable url rewrite in apache.conf ) , if this won't work then try base_url/index.php/example ( where you can specify base_url by static or with CodeIgniter helpher function )
xmlhttp.send();
</script>

Nest Step

example.php should look like this

class example extends CI_Controller {
    public function index()
    {
        echo "OKKK";
    }
}