if a website does not have jQuery, and we want to use jQuery in chrome console.
You can copy the code from here
http://code.jquery.com/jquery-latest.min.js
paste it into chrome console, then you are good to go.
http://stackoverflow.com/questions/7474354/include-jquery-in-the-javascript-console
原文：http://www.cnblogs.com/phoenix13suns/p/4582255.html