JavaScript - Date Prompts - Dynamic/Onchange updation

[cognosun]

I have 2 Date prompts in the prompt page ( date1 and date2):

If user selects a value from date1 ( say 30th march 2016) then the value in the second prompt (date2) should change to 23rd March 2016.

Is there any javascript which will do this dynamic task....related to onchage funtionality.

There are some similar posts in this site related to manual updation in textbox prompt, but is there any script for Date prompts in particular ?

Many thanks in advance

[BigChris]

Is the second prompt really a prompt, or do you always want it to be 7 days prior to the date in the first prompt?

[cognosun]

It's a Date prompt too.

[bdbits]

I think what BigChris is asking is: are you just being helpful to the user, or do you always want the second date to be 7 days earlier than the first? If it is always going to be the same 7 day offset, you don't need the prompt at all and you can simply make the calculation in your date filter/slicer.

[BigChris]

You're right - that's exactly what I was asking  :D