Shortening JADE templating code?

Question

JavaScript

if user.familyName
    input.txt#familyName(type="text",value="#{user.familyName}" name="familyName" ,required ,placeholder="Введите Фамилию")
else
    input.txt#familyName(type="text",name="familyName" ,required ,placeholder="Введите Фамилию")

And there can be many more such checks
. How can I more gracefully shorten the above code?

Answer 1

input.txt#familyName(value="#{user ? user.familyName : ''}", type="text", name="familyName", required, placeholder="Введите Фамилию")

Well, for more serious things - mixins make it great not to write the same thing ten times.