Adding Carbon Fields to Yoast SEO content analysis

yoast-seo-carbon-fields.js

/**
 * Adds specified Carbon Field to the Yoast SEO content analysis.
 *
 * @link https://return-true.com/adding-content-to-yoast-seo-analysis-using-yoastseojs/
 * @link https://kb.yoast.com/kb/can-i-add-data-to-the-page-analysis/
 * @link https://github.com/Yoast/YoastSEO.js/blob/master/README.md
 * @link https://github.com/Yoast/YoastSEO.js/issues/181#issuecomment-163162489
 */
(function($) {

    var MyYoastPlugin = function()
    {
        YoastSEO.app.registerPlugin('carbonFieldIntroText', {status: 'loading'});

        this.getData();
    };

    MyYoastPlugin.prototype.getData = function()
    {

        var _self = this,
            $text = $('#carbon-field-7');

        _self.custom_content = $text.val();

        YoastSEO.app.pluginReady('carbonFieldIntroText');

        YoastSEO.app.registerModification('content', $.proxy(_self.getCustomContent, _self), 'carbonFieldIntroText', 5);

    };

    MyYoastPlugin.prototype.getCustomContent = function (content)
    {
        return this.custom_content + content;
    };

    $(window).on('YoastSEO:ready', function ()
    {
        new MyYoastPlugin();
    });
})(jQuery);

yoast-seo-carbon-fields.php

<?php
/**
 * Carbon Fields and Yoast SEO modifications
 *
 * @package     NickDavis\Theme\Admin
 * @since       1.0.0
 * @author      Nick Davis
 * @link        https://iamnickdavis.com
 * @license     GNU General Public License 2.0+
 */

namespace NickDavis\Theme\Admin;

add_action( 'admin_enqueue_scripts', __NAMESPACE__ . '\enqueue_yoast_seo_analysis_carbon_fields_script' );
/**
 * Adds selected Carbon Fields to Yoast SEO content analysis.
 *
 * @since 1.0.0
 *
 * @link https://return-true.com/adding-content-to-yoast-seo-analysis-using-yoastseojs/
 * @link https://kb.yoast.com/kb/can-i-add-data-to-the-page-analysis/
 * @link https://github.com/Yoast/YoastSEO.js/blob/master/README.md
 * @link https://github.com/Yoast/YoastSEO.js/issues/181#issuecomment-163162489
 */
function enqueue_yoast_seo_analysis_carbon_fields_script() {
	wp_enqueue_script( 'yoast-seo-carbon-fields', CHILD_THEME_URL . '/assets/js/admin/yoast-seo-carbon-fields.js', array( 'jquery', 'yoast-seo-admin-script' ) );
}