Bootstrap 4 Breadcrumb Markup for Yoast SEO Breadcrumb

bootstrap4-yoast-seo-breadcrumb.php

/***************************************
 * Add this code to theme functions.php
 ***************************************/

/**
 * @param $wrapper
 *
 * @return string
 */
function customWpseoBreadcrumbOutputWrapper($wrapper)
{
	return 'ol';
}
add_filter('wpseo_breadcrumb_output_wrapper', 'customWpseoBreadcrumbOutputWrapper', 10, 1);

/**
 * @param $class
 *
 * @return string
 */
function customWpseoBreadcrumbOutputClass($class)
{
	return 'breadcrumb';
}
add_filter('wpseo_breadcrumb_output_class', 'customWpseoBreadcrumbOutputClass', 10, 1);

/**
 * @param $separator
 *
 * @return string
 */
function customWpseoBreadcrumbSeparator($separator)
{
	return '';
}
add_filter('wpseo_breadcrumb_separator', 'customWpseoBreadcrumbSeparator', 10, 1);

/**
 * @param $wrapper
 *
 * @return string
 */
function customWpseoBreadcrumbSingleLinkWrapper($wrapper) {
	return 'li';
}
add_filter('wpseo_breadcrumb_single_link_wrapper', 'customWpseoBreadcrumbSingleLinkWrapper', 10, 1);

/**
 * @param $link_output
 * @param $link
 *
 * @return string|string[]
 */
function customWpseoBreadcrumbSingleLink($link_output, $link)
{
	return str_replace(
		array(
			'<li>',
			'<span class="breadcrumb_last" aria-current="page">',
			'</span>'
		),
		array(
			'<li class="breadcrumb-item">',
			'</li><li class="breadcrumb-item active" aria-current="page">',
			'</li>'
		),
		$link_output);
}
add_filter('wpseo_breadcrumb_single_link', 'customWpseoBreadcrumbSingleLink', 10, 2);