Filling rows based by iterating on different column entity

[#1]

I want to assign a value to each row within a category defined in another column using JSL. For example, Module is the Category column and I want to assign this to All rows in within that category in the New column. 

the new column should be like this 

[#2 · Accepted solution]

If( :Module != "",
	value = :Module
);
value;

[#3]

Or if you can modify Module column you can fill it

[#4]

Unfortunately, in my case there are thousands of Modules in the module column, so doing it manually is not an option. I believe I will have to use for & if loop to fill the New Column with Module value

[#5]

Is there an issue with the column formula that I provided.  It will work with thousands of Modules?

[#6]

Looks like your formula works perfectly, Jim.

[#7]

It is few button presses to fill them in by replacing with previous value. It isn't automated and if you don't need it automated, it should work fine. Other excellent options if the formula Jim has provided you with.