Retrieving list of a custom post type in a widget without using WP_Query?

Use wp_reset_postdata() function after while loop to reset custom wp_query as shown in following code so that it will not break other wordpress loop.

  <?php // Create and run custom loop
    $custom_posts = new WP_Query();
    $custom_posts->query('post_type=jobs&posts_per_page=8');
    while ($custom_posts->have_posts()) : $custom_posts->the_post();
  ?>
    <li><a href="https://wordpress.stackexchange.com/questions/98851/<?php the_permalink(); ?>"><?php the_title(); ?></a></li>
  <?php endwhile; ?>
  <?php wp_reset_postdata(); ?>

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