A customized recent posts widget for WordPress. Find the full tutorial for implementing the widget in my blog.

widget-recent-posts.php

<?php
/**
 * Widget for a Recent Posts
 */


 // Register and load the widget
function load_custom_widget() {
    register_widget('Custom_Recent_Posts_Widget');
}
add_action('widgets_init', 'load_custom_widget');

// Widget Class
class Custom_Recent_Posts_Widget extends WP_Widget {

	/**
	 * Sets up a new Recent Posts widget instance.
	 *
	 * @since 2.8.0
	 */
	// Name the new widget and extend the core functioning
    public function __construct() {
        $widget_ops = array(
            'classname' => 'custom-recent-posts',
            'description' => __( 'Custom recent posts widget' ),
            'customize_selective_refresh' => true,
        );

        parent::__construct( 'custom-recent-posts', __( 'Custom Recent Posts' ), $widget_ops );
        $this->alt_option_name = 'widget_recent_blog_posts';
    }

	/**
	 * Outputs the content for the current Recent Posts widget instance.
	 *
	 * @since 2.8.0
	 *
	 * @param array $args     Display arguments including 'before_title', 'after_title',
	 *                        'before_widget', and 'after_widget'.
	 * @param array $instance Settings for the current Recent Posts widget instance.
	 */
	public function widget( $args, $instance ) {
		if ( ! isset( $args['widget_id'] ) ) {
			$args['widget_id'] = $this->id;
		}

		$title = ( ! empty( $instance['title'] ) ) ? $instance['title'] : __( 'Recent Posts' );

		/** This filter is documented in wp-includes/widgets/class-wp-widget-pages.php */
		$title = apply_filters( 'widget_title', $title, $instance, $this->id_base );

		$number = ( ! empty( $instance['number'] ) ) ? absint( $instance['number'] ) : 5;
		if ( ! $number ) {
			$number = 5;
		}
		
		$show_date = isset( $instance['show_date'] ) ? $instance['show_date'] : false;

		// add the new widget options to be processed and diplayed as html
		$show_excerpt = isset($instance['show_excerpt']) ? $instance['show_excerpt'] : false;
		$show_link    = isset($instance['show_link']) ? $instance['show_link'] : false;

		/**
		 * Filters the arguments for the Recent Posts widget.
		 *
		 * @since 3.4.0
		 * @since 4.9.0 Added the `$instance` parameter.
		 *
		 * @see WP_Query::get_posts()
		 *
		 * @param array $args     An array of arguments used to retrieve the recent posts.
		 * @param array $instance Array of settings for the current widget.
		 */
		$r = new WP_Query(
			apply_filters(
				'widget_posts_args',
				array(
					'posts_per_page'      => $number,
					'no_found_rows'       => true,
					'post_status'         => 'publish',
					'ignore_sticky_posts' => true,
				),
				$instance
			)
		);

		if ( ! $r->have_posts() ) {
			return;
		}
		?>
		<?php echo $args['before_widget']; ?>
		<?php
		if ( $title ) {
			echo $args['before_title'] . $title . $args['after_title'];
		}
		?>
		<ul>
			<?php foreach ( $r->posts as $recent_post ) : ?>
				<?php
				$post_title   = get_the_title( $recent_post->ID );
				$title        = ( ! empty( $post_title ) ) ? $post_title : __( '(no title)' );
                $aria_current = '';
                $post_excerpt = get_the_excerpt($recent_post->ID);
                $post_excerpt = wp_trim_words($post_excerpt, 10); // re-assign variable and trim excerpt to 10 words

				if ( get_queried_object_id() === $recent_post->ID ) {
					$aria_current = ' aria-current="page"';
				}
				?>
				<li>
					<a href="<?php the_permalink( $recent_post->ID ); ?>"<?php echo $aria_current; ?>><?php echo $title; ?></a>
					<?php if ( $show_date ) : ?>
						<span class="post-date"><?php echo get_the_date( '', $recent_post->ID ); ?></span>
                    <?php endif; ?>
                    
                    <?php if ( $show_excerpt ) : ?>
                        <p class="post-excerpt"><?php echo $post_excerpt; ?></p>
                    <?php endif; ?>

                    <?php if ( $show_link ) : ?>
                        <a href="<?php the_permalink($recent_post->ID); ?>" class="post-read-more">Read More</a>
                    <?php endif; ?>
				</li>
			<?php endforeach; ?>
		</ul>
		<?php
		echo $args['after_widget'];
	}

	/**
	 * Handles updating the settings for the current Recent Posts widget instance.
	 *
	 * @since 2.8.0
	 *
	 * @param array $new_instance New settings for this instance as input by the user via
	 *                            WP_Widget::form().
	 * @param array $old_instance Old settings for this instance.
	 * @return array Updated settings to save.
	 */
	public function update( $new_instance, $old_instance ) {
		$instance              = $old_instance;
		$instance['title']     = sanitize_text_field( $new_instance['title'] );
		$instance['number']    = (int) $new_instance['number'];
        $instance['show_date'] = isset( $new_instance['show_date'] ) ? (bool) $new_instance['show_date'] : false;
        
        // add the custom widget options to be saved to the database
        $instance['show_excerpt'] = isset( $new_instance['show_excerpt'] ) ? (bool) $new_instance['show_excerpt'] : false;
        $instance['show_link'] = isset( $new_instance['show_link'] ) ? (bool) $new_instance['show_link'] : false;
		return $instance;
	}

	/**
	 * Outputs the settings form for the Recent Posts widget.
	 *
	 * @since 2.8.0
	 *
	 * @param array $instance Current settings.
	 */
	public function form( $instance ) {
		$title     = isset( $instance['title'] ) ? esc_attr( $instance['title'] ) : '';
		$number    = isset( $instance['number'] ) ? absint( $instance['number'] ) : 5;
        $show_date = isset( $instance['show_date'] ) ? (bool) $instance['show_date'] : false;
        
        // add the custom widget options to be shown in the widget form on the Widgets page:
        $show_excerpt = isset($instance['show_excerpt']) ? (bool) $instance['show_excerpt'] : false;
        $show_link    = isset($instance['show_link']) ? (bool) $instance['show_link'] : false;
		?>

		<p><label for="<?php echo $this->get_field_id( 'title' ); ?>"><?php _e( 'Title:' ); ?></label>
		<input class="widefat" id="<?php echo $this->get_field_id( 'title' ); ?>" name="<?php echo $this->get_field_name( 'title' ); ?>" type="text" value="<?php echo $title; ?>" /></p>

		<p><label for="<?php echo $this->get_field_id( 'number' ); ?>"><?php _e( 'Number of posts to show:' ); ?></label>
		<input class="tiny-text" id="<?php echo $this->get_field_id( 'number' ); ?>" name="<?php echo $this->get_field_name( 'number' ); ?>" type="number" step="1" min="1" value="<?php echo $number; ?>" size="3" /></p>

		<p><input class="checkbox" type="checkbox"<?php checked( $show_date ); ?> id="<?php echo $this->get_field_id( 'show_date' ); ?>" name="<?php echo $this->get_field_name( 'show_date' ); ?>" />
        <label for="<?php echo $this->get_field_id( 'show_date' ); ?>"><?php _e( 'Display post date?' ); ?></label></p>
        
        <p><input class="checkbox" type="checkbox"<?php checked( $show_excerpt ); ?> id="<?php echo $this->get_field_id( 'show_excerpt' ); ?>" name="<?php echo $this->get_field_name( 'show_excerpt' ); ?>" />
        <label for="<?php echo $this->get_field_id( 'show_excerpt' ); ?>"><?php _e( 'Display post excerpt?' ); ?></label></p>
        
        <p><input class="checkbox" type="checkbox"<?php checked( $show_link ); ?> id="<?php echo $this->get_field_id( 'show_link' ); ?>" name="<?php echo $this->get_field_name('show_link' ); ?>" />
        <label for="<?php echo $this->get_field_id( 'show_link' ); ?>"><?php _e( 'Display read more link?' ); ?></label></p>

		<?php
	}
}