if input maybe undefined how to use swig date filter

Question

I use swig in my nodejs project，when use date filter，I found this：

{{t.updateAt|date('Y-m-d H:i:s',-480)}}
NaN-NaN-NaN NaN:NaN:NaN

because sometimes t.updateAt is undefined, when this time I need date filter output ''.

so, How can I do?

Answer 1

{% if t.updateAt %}
    {{t.updateAt|date('Y-m-d H:i:s',-480)}}
{% endif %}