What is the best way to modify the JavaScript included in a scraped web page?

What is the best way to modify the JavaScript included in a scraped web page?

References

Reference NO 1

http://stackoverflow.com/questions/17919087/scraping-a-web-page-javascript

Reference NO 2

http://stackoverflow.com/questions/1700415/whats-the-best-way-to-write-a-maintainable-web-scraping-app

Reference NO 3

http://blog.hartleybrody.com/web-scraping/

Reference NO 4

http://net.tutsplus.com/tutorials/javascript-ajax/how-to-scrape-web-pages-with-node-js-and-jquery/

Reference NO 5

http://blog.miguelgrinberg.com/post/easy-web-scraping-with-nodejs

Reference NO 6

http://en.wikipedia.org/wiki/Web_scraping

Reference NO 7

http://ruby.bastardsbook.com/chapters/web-scraping/

Reference NO 8

http://programmers.stackexchange.com/questions/151739/getting-data-from-a-webpage-in-a-stable-and-efficient-way