Capybara helper for calling evaluate_script with multiple lines of JavaScript, supporting short-circuit return statements, etc etc. Just wraps your JS in a function and then calls it.

evaluate_multiline_script.rb

# Given a multiline script, this will wrap the script in a function and then 
# call it so Capybara's evaluate_script knows how to get the return value properly. 
# By default, Capybara just prepends a 'return ' to your script.
#
# Usage:
#
#     value = page.evaluate_multiline_script %{
#       var foo = [];
#       $('li').each(function(i, li) {
#         foo[foo.length] = $(li).text();
#       });
#       return foo;
#     }
#
class Capybara::Session
  def evaluate_multiline_script javascript
    evaluate_script "(function(){ #{javascript} })()"
  end
end