Wordpress custom widget extending wp-widget class

Banner Widget

/**
*
*   Banner Widget
*   Note* - The WP_Widget class is located in wp-includes/class-wp-widget.php.
*/

class Banner_Widget extends WP_Widget {

	/**
	 * Register Widget With Wordpress
	 */
	public function __construct() {
		parent::__construct(
			'banner_widget', // Base ID
			__('Banner Widget', 'text_domain'), // Widget name
			array( 'description' => __( 'Greg Reid Banner Widget', 'text_domain' ), )
        );
	}

	/**
	 * Back-end widget form.
	 *
	 * @see WP_Widget::form()
	 *
	 * @param array $instance Previously saved values from database.
	 */

	public function form( $instance ) {
 
        // if text contain a value, save it to $link
        if ( isset( $instance[ 'link' ] ) ) {
            $link = $instance[ 'link' ];
        }          
        // if text contain a value, save it to $text
        if ( isset( $instance[ 'text' ] ) ) {
            $text = $instance[ 'text' ];
        }        
        // if text contain a value, save it to $subtitle
        if ( isset( $instance[ 'subtitle' ] ) ) {
            $subtitle = $instance[ 'subtitle' ];
        }
        // if title contain a value, save it to $title
        if ( isset( $instance[ 'title' ] ) ) {
            $title = $instance[ 'title' ];
        }
        else {
            // else set the $title to string - Title
            $title = __( 'Title', 'text_domain' );
        }
        ?>
        <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 esc_attr( $title ); ?>">
        </p>        

        <p>
        <label for="<?php echo $this->get_field_id( 'subtitle' ); ?>"><?php _e( 'Sub-Title:' ); ?></label> 
        <input class="widefat" id="<?php echo $this->get_field_id( 'subtitle' ); ?>" name="<?php echo $this->get_field_name( 'subtitle' ); ?>" type="text" value="<?php echo esc_attr( $subtitle ); ?>">
        </p>
 
        <p>
        <label for="<?php echo $this->get_field_id( 'text' ); ?>"><?php _e( 'Description:' ); ?></label> 
        <textarea rows="8" cols="40" class="widefat" id="<?php echo $this->get_field_id( 'text' ); ?>" name="<?php echo $this->get_field_name( 'text' ); ?>"><?php echo esc_attr( $text ); ?>
        </textarea>
        </p>

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

	// array $instance Stores values from database.
	    public function widget( $args, $instance ) {
	        $title = apply_filters( 'widget_title', $instance['title'] );
	 
	        echo $args['before_widget'];

	        if ( ! empty( $title ) )
	            echo $args['before_title'] . '<h1 class=">' . 'bw-banner-title">' . $title . '</h1>' . $args['after_title'];

            echo '<p class=' . 'bw-subtitle>' . ' <b>' . $instance['subtitle'] . '</b></p>';
            echo '<div class=' . 'bw-banner-textarea' . '>' . $instance['text'];
            echo $args['after_widget'];
            echo '<a class="' . 'bw-link" ' . 'href="' . $instance['link'] . '"' . '>' . '<button>INVITE GREG TO SPEAK</button>'. '</p>';
	    }

	/**
	 * Sanitize widget form values as they are saved.
	 *
	 * @see WP_Widget::update()
	 *
	 * @param array $new_instance Values just sent to be saved.
	 * @param array $old_instance Previously saved values from database.
	 *
	 * @return array Updated safe values to be saved.
	 */

		public function update( $new_instance, $old_instance ) {
		        $instance = array();

		        $instance['title'] = ( ! empty( $new_instance['title'] ) ) ? strip_tags( $new_instance['title'] ) : '';	        

		        $instance['subtitle'] = ( ! empty( $new_instance['subtitle'] ) ) ? strip_tags( $new_instance['subtitle'] ) : '';

		        $instance['text'] = ( ! empty( $new_instance['text'] ) ) ? strip_tags( $new_instance['text'] ) : '';

		        $instance['link'] = ( ! empty( $new_instance['link'] ) ) ? strip_tags( $new_instance['link'] ) : '';
		 
		        return $instance;
		}

} // Banner Widget Class

add_action( 'widgets_init', function(){
	register_widget( 'Banner_Widget' );
});