How to check for null in Twig?

Question

What construct should I use to check whether a value is NULL in a Twig template?

Answer 1

How to set default values in twig: http://twig.sensiolabs.org/doc/filters/default.html

{{ my_var | default("my_var doesn't exist") }}

Or if you don't want it to display when null:

{{ my_var | default("") }}