Change the default value of date input

i want to change the default value of date input plz help me!

Hi @hamedebi What’s the use case?

I want to work with the Persian calendar!

You might want to look for a standard plugin. All date objects are built here:

Tanx for reply.
My scenario is add ‘base calendar type’ to user profile with two option ‘Gregorian’ and ‘Solar’ . after user select Solar Base Calendar Type , i want change date picker and replace them with my Persian control for display date and time in Solar calendar format.
my local js control for Solar and Gregorian calendar attached.
How apply this use case replacement?