Yoast Subtitle Analyzer

yoast-analyzer-subtitle.js

/**
 * Source: https://wordpress.org/plugins/meta-box-yoast-seo
 */

/* global jQuery, DS1_fields */

// My custom metabox subtitle input id
var DS1_fields = ['acf-field_54da15f9ad3c2'];

(function (fields) {
    var module = {
        // Initialize
        init: function() {
            jQuery(window).on('YoastSEO:ready', module.load);
        },

        // Load plugin and add hooks.
        load: function() {
            YoastSEO.app.registerPlugin('ds1_subtitle', {status: 'ready'});
            YoastSEO.app.registerModification('title', module.addContent, 'ds1_subtitle');
            module.bind();
        },

        // Add content to Yoast SEO Analyzer.
        addContent: function(content) {
            fields.map(function(fieldId) {
                content += ' ' + document.getElementById(fieldId).value;
            });
            return content;
        },

        // Update Yoast SEO analyzer when fields are updated.
        // Use debounce technique, which triggers refresh only when keys stop being pressed.
        bind: function() {
            var timeout;

            function refresh() {
                clearTimeout(timeout);
                timeout = setTimeout(function() {
                    YoastSEO.app.refresh();
                }, 250);
            }

            fields.map(function(fieldId) {
                document.getElementById(fieldId).addEventListener('keyup', refresh);
            });
        }
    };

    module.init();
})(DS1_fields);