Icons to navigation

icon-nav.php

<?php
/**
 * Add SVG icon for dropdown in primary navigation.
 *
 * @since 1.0.0
 *
 * @param string  $item_output The menu item output.
 * @param WP_Post $item        Menu item object.
 * @param int     $depth       Depth of the menu.
 * @param array   $args        wp_nav_menu() arguments.
 * @return string Menu item with SVG icon.
 */
function checathlon_dropdown_icon_to_menu_links( $item_output, $item, $depth, $args ) {
	
	if ( 'primary' == $args->theme_location ) {
	
		foreach ( $item->classes as $value ) {
			if ( $value == 'menu-item-has-children' ) {
				//$item_output =  $item_output . checathlon_get_svg( array( 'icon' => 'expand' ) );
				//$item_output = str_replace( $args->link_after, '</span>' . checathlon_get_svg( array( 'icon' => 'expand' ) ), $item_output );
				$item_output = str_replace( '</a>', checathlon_get_svg( array( 'icon' => 'expand' ) ) . '</a>', $item_output );

			}
		}
		
	}
	
	return $item_output;
	
}
add_filter( 'walker_nav_menu_start_el', 'checathlon_dropdown_icon_to_menu_links', 10, 4 );