How to inject jQuery code on a page, strictly client side - Chrome? -

i'm wondering if there's way in chrome can execute .js file on rendered page i'm viewing? in other words, i'd able visit site have no control on (e.g. stackoverflow.com), , execute below code example:

$('body').fadeout('slow'); 

i type in console, , works, let's there's whole bunch of jquery code wanted run , test out. there way can this?

have looked greasemonkey chrome?