<?PHP
//embed heartbeat api
    function heartbeat_test_enqueue($hook_suffix) {
            if ( is_page(1105)) {
                // Make sure the JS part of the Heartbeat API is loaded.
                wp_enqueue_script('heartbeat');

                // Output the test JS in footer.
                add_action( 'print_footer_scripts', 'heartbeat_test_js', 20 );

                //Add filter to receive hook, and specify we need 2 parameters.
                add_filter( 'heartbeat_received', 'dw_receive_heartbeat', 10, 2 );
            }

    }
    add_action( 'wp_enqueue_scripts', 'heartbeat_test_enqueue' );


    //clientside
    function heartbeat_test_js() {
            ?>
            <script>

            jQuery(document).ready( function($) {
                    // Hook into the heartbeat-send
                    jQuery( document ).on( 'heartbeat-send', function( e, data ) {
                        //
                    });

                    // Listen for the custom event "heartbeat-tick" on $(document). This fire's once every minute that the page is open.
                    jQuery(document).on( 'heartbeat-tick', function(e, data) {
                        console.log("tick");
                    });
            });

            </script>
            <?php
    }


    //change heartbeat interval time
    function m_heartbeat_settings( $settings ) {
       $settings['interval'] = 15; //only values between 15 and 60 seconds allowed
       return $settings;
    }
    add_filter( 'heartbeat_settings', 'm_heartbeat_settings' );

    //heartbeat api end
?>