re = /.*(?<=email&jobId\=)(\d+)(?=&distance).*/
str = '/visitor/browseJobDetails.do?comeFrom=email&jobId=3931052&distance=18&rx=email_NJNY%7CProvider_Featured%7Cjobtitle%7C91942%7CCHILDCARE`'
# Print the match result
str.match(re) do |match|
puts match.to_s
end
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html