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

def get_code(str)
  str.sub(/^(Z_.*): .*/, '\1')
end
get_code('Z_foo: bar!') # => "Z_foo"