A way for static "now" in google sheet?

Question

I would like to insert a formula with a checklist. That is, when I check the checklist, I want the date and time when I did it to appear in the cell next to it. Obviously, however, the "now" formula is updated with each click of the checklists, and I want the date when I checked it to remain. How can I enter a static date? if you have to use VBA, how do you open it? would it be google script? help!

i've tried this formula

=if(C1="true";if(C2;C2;now());"") 

but it works only if is FALSE....and no data.

Answer 1

Replace your references to now() with lambda(x;x)(now()). Volatile functions (like NOW, RAND,etc.) can be made 'sticky' by encapsulating them in a LAMBDA like this.