what is the difference between these two types of widget form method

Question

    $title = isset( $instance['title'] ) ? $instance['title'] : '';

and

        $title               = strip_tags($instance['title']);

what is the difference between the above two?

Do they perform the one and the same action in the widget form method? Or I am mistaking something as they have different functions or one is used in widget form function and the another one is used in the widget's widget method?

Or they just the difference of coding practice?

Or if they are performing the same action then we can combine them and make a better fusion like this →

$title = isset( $instance['title'] ) ? strip_tags($instance['title']) : '';

Please also help me to understand what is the role of this here → ?

Answer 1

It is just a PHP coding practice difference and you can combine both. The use of ?: is called ternary operator and it is like a if/else shorthand. This line:

 $title = isset( $instance['title'] ) ? $instance['title'] : '';

It is like:

if( isset( $instance['title'] ) ) {
    $title = isset( $instance['title'] );
} else {
    $title = '';
}

If you see core widgets, they usually use the ternary operator, but is just a coding preference. For example, you can see this code in Archives widget:

$title = apply_filters( 'widget_title', empty( $instance['title'] ) ? __( 'Archives' ) : $instance['title'], $instance, $this->id_base );

Or this one in Calendar widget:

$title = apply_filters( 'widget_title', empty( $instance['title'] ) ? '' : $instance['title'], $instance, $this->id_base );

Applying the widget_title it is more important to me than using or not ternary operators; you shouldn't forget it.