How to call ajax in wordpress

My ajax call output is always showing 0 as output don’t know why

In functions.php I have this code

function get_data() {
    $abc = '1';
    $result = $wpdb->get_results("SELECT * FROM ".$wpdb->options ." WHERE option_name LIKE '_transient_%'");
    echo  $result; //returning this value but still shows 0
    wp_die();
}

add_action( 'wp_ajax_nopriv_get_data', 'get_data' );
add_action( 'wp_ajax_get_data', 'get_data' );

And my ajax call is in a javascript

$('body').on("click", ".re-reset-btn", function(e){

    var panel = $('#re-compare-bar');       

    $.ajax({
             type : "GET",
             dataType : "json",
             url : "/wp-admin/admin-ajax.php",
             data : {action: "get_data"},
             success: function(response) {

                   alert("Your vote could not be added");
                   alert(response);
                }
        });   

    $("#re-compare-bar-tabs div").remove(); 
    $('.re-compare-icon-toggle .re-compare-notice').text(0); 

});

I’m making ajax call in wordpress without use of plugin but not getting what I’m passing.Even If I output $abc still it shows 0.

Answer

In backend there is global ajaxurl variable defined by WordPress itself.

This variable is not created by WP in frontend. It means that if you want to use AJAX calls in frontend, then you have to define such variable by yourself.

Good way to do this is to use wp_localize_script.

Let’s assume your AJAX calls are in my-ajax-script.js file, then add wp_localize_script for this JS file like so:

function my_enqueue() {
      wp_enqueue_script( 'ajax-script', get_template_directory_uri() . '/js/my-ajax-script.js', array('jquery') );
      wp_localize_script( 'ajax-script', 'my_ajax_object', array( 'ajax_url' => admin_url( 'admin-ajax.php' ) ) );
 }
 add_action( 'wp_enqueue_scripts', 'my_enqueue' );

After localizing your JS file, you can use my_ajax_object object in your JS file:

jQuery.ajax({
    type: "post",
    dataType: "json",
    url: my_ajax_object.ajax_url,
    data: formData,
    success: function(msg){
        console.log(msg);
    }
});