WordPress Basic Ajax Handling

wordpress-basic-ajax.txt

Requirements
-------------------------
In wp-admin you do not need to do anything, the js library is always loaded
In the front-end you need to enqueue the script wp-util, like this:

add_action( 'wp_enqueue_scripts', 'my_enqueue_function' );

function my_enqueue_function() { 
    // Option 1: Manually enqueue the wp-util library.
    wp_enqueue_script( 'wp-util' );

    // Option 2: Make wp-util a dependency of your script (usually better).
    wp_enqueue_script( 'my-script', 'my-script.js', [ 'wp-util' ] );
}

The JS Library
---------------------------
The wp-util script contains the wp.ajax object that you can use to make ajax requests:

wp.ajax.post( action, data ).done( okCallback ).fail( errCallback )

Your example:
wp.ajax.post( "get_data", {} )
  .done(function(response) {
    alert("Your vote could not be added");
    alert(response);
  });
 
 
PHP code
----------------------------
Of course, you still need to create the wp_ajax_* hooks in your PHP script.

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

function my_ajax_handler() {
    wp_send_json_success( 'It works' );
}

Tip:
For Ajax responses WordPress provides two functions:

wp_send_json_success( $my_data ) and wp_send_json_error( $my_data )

both functions return a JSON object and instantly terminate the request (i.e., they exit;)