update_option in javascript

Question

So there's function in wordpress to update a named option/value pair to the options database table: <?php update_option( $option, $new_value ); ?>. And what I'm trying to do implement this function in javascript so when you hit the bottom of the page an option would update. I am using this script to check when you hit bottom of the page:

$(window).scroll(function () {
   if ($(window).scrollTop() >= $(document).height() - $(window).height() - 10) {
      /***update options***/
   }
});

So my question is how to implement update_option function into javascript.

Answer 1

JavaScript

$(window).scroll(function () {
    if ($(window).scrollTop() >= $(document).height() - $(window).height() - 10) {
        /***update options***/
        $.ajax({
            type:   'POST',
            url:    'http://www.example.com/wp-admin/admin-ajax.php',
            data:   {
                action    : 'hit-bottom',
                option    : $option, // your option variable
                new_value : $new_value // your new value variable
            },
            dataType: 'json'
        }).done(function( json ) {
            alert( "Ajax call succeeded, let's see what the response was." );
            if( json.success ) {
                alert( "Function executed successfully and returned: " + json.message );
            } else if( !json.success ) {
                alert( "Function failed and returned: " + json.message );
            }
        }).fail(function() {
            alert( "The Ajax call itself failed." );
        }).always(function() {
            alert( "This message is always displayed, whether the call failed or succeeded." );
        });
    }
});

functions.php

/* hit bottom of screen event  */
add_action( 'wp_ajax_hit-bottom', 'wpse_hit_bottom' );
add_action( 'wp_ajax_nopriv_hit-bottom', 'wpse_hit_bottom' );
function wpse_hit_bottom() {
    $option = $_POST['option'];
    $new_value = $_POST['new_value'];

    if( !isset( $option ) || $option == '' || !isset( $new_value ) || $new_value = '' ) {
        die(
            json_encode(
                array(
                    'success' => false,
                    'message' => 'Missing required information.'
                )
            )
        );
    }

    update_option( $option, $new_value );
    die(
        json_encode(
            array(
                'success' => true,
                'message' => 'Database updated successfully.'
            )
        )
    );
}