Ruby replace string with captured regex pattern

Question

I am having trouble translating this into Ruby.

Here is a piece of JavaScript that does exactly what I want to do:

function get_code(str){
    return str         


        

Answer 1

Try '\1' for the replacement (single quotes are important, otherwise you need to escape the \):

"foo".gsub(/(o+)/, '\1\1\1')
#=> "foooooo"

But since you only seem to be interested in the capture group, note that you can index a string with a regex:

"foo"[/oo/]
#=> "oo"
"Z_123: foobar"[/^Z_.*(?=:)/]
#=> "Z_123"