Coding up some javascript is often an exciting and debuggery filled exercise, with much time spent hopping between your text/code editing device and your browser, hammering away at f5 or clearing some cache.
And when javascript results are not what you're intending to see it is a delightful, delicate, and disciplined dance that developers then do - a sprinkle of a firebug add-on here, or maybe you will toss in a dash of Internet Explorer's Developer tools, or maybe you prefer the surprisingly strong new-ish flavor on the block, Google Chrome's "...