Return post titles from post IDs array as string with passed delimiter

jet-search-add-custom-meta-callback.php

<?php
	add_filter( 'jet-search/ajax-search/meta_callbacks', '__your_prefix_add_meta_callback' );

	function __your_prefix_add_meta_callback( $callbacks ) {
		$callbacks['__your_prefix_get_post_title_by_id'] = esc_html__( 'Get post title by ID', 'jet-search' );
		return $callbacks;
	}

	function __your_prefix_get_post_title_by_id( $value = null, $delimiter = ', ' ) {

		if ( ! $value || ! is_array( $value ) ) {
			return $value;
		}

		return wp_kses_post( implode( $delimiter, array_map( 'get_the_title', $value ) ) );

	}