Q: ReferenceError: ajax_object is not defined Hi i have this script when link is click the data will be saved into the database. Now my problem is after clicking the link this is the error:
ReferenceError: ajax_object is not defined

This is my script below in single-knowledge page
<script type="text/javascript">
    jQuery(document).ready(function($) {
        $(".dL").click(function(){
            var name = ($(this).attr('name'));
            var urldata = ($(this).attr('href'));

            var data = {
                'action': 'my_action',
                'name': name,
                'urldata': urldata // We pass php values differently!
            };


            // We can also pass the url value separately from ajaxurl for front end AJAX implementations
            jQuery.post(ajax_object.ajax_url, data, function(response) {
                // alert('Got this from the server: ' + response);
                alert(response);
            });

        });


    });

</script>

This is my function.php script below
 function my_action(){
        global $wpdb; // this is how you get access to the database

        $name = $_POST['name'];
        $url = $_POST['urldata'];


        $wpdb->insert('list_of_downloads', array(
            'name' => $name,
            'filename' =>$url
        ));

       // wp_die(); // this is required to terminate immediately and return a proper response
    }


    add_action( 'wp_ajax_my_action', 'my_action' );
    add_action( 'wp_ajax_nopriv_my_action', 'my_action' ); // <= this one

The problem is this one ajax_object
Can someone help me figured this thing out? Any help is muchly appreciatd.
TIA

A: You are getting error because you didn't declare that variable. Since you are trying to call function through ajax using wordpress, so i would like to share what i have done recently. 
Add following script in your function.php which will add the admin-ajax.php url in the header. 
add_action( 'init', 'my_script_enqueuer' );

function my_script_enqueuer() {
    wp_enqueue_script( 'add-order-front',  get_template_directory_uri() . '/js/ajax.js' );
    wp_localize_script( 'add-order-front', 'MyAjax', array( 'ajaxurl' => admin_url( 'admin-ajax.php' ) ) );

   wp_enqueue_script( 'jquery' );
   wp_enqueue_script( 'add-order-front' );

}

Then use following ajax script for calling that function.
jQuery(document).on('click','.dL',function(){
    var name = ($(this).attr('name'));
    var urldata = ($(this).attr('href'));
    jQuery.ajax({
        type : 'POST',
        url  : MyAjax.ajaxurl,
        data: {action: 'my_action','name': name,'urldata': urldata}, 
        dataType:"json",
        success:function(data){
            console.log(data);                  
        },
        error: function(data){
            console.log(data);
        }
    });
});

The above script is working for me. 

A: I don't see anywhere that you declared 'ajax_object'. You can use it like below, if your server side code on file 'function.php':
// We can also pass the url value separately from ajaxurl for front end AJAX implementations
jQuery.post("function.php", data, function(response) {
   // alert('Got this from the server: ' + response);
   alert(response);
});

