Based on coincidental recommendations from both Daryn Nakhuda and Mark Foster on the Seattle Tech Startups mailing list, and Douglas Crockford of JSON fame, I installed the YSlow plugin for Firefox.  This is a Yahoo-developed plugin that runs within the Firebug environment, which I already know and love.

My  immediate need was for something to help debug a couple JSON problems I’ve run into lately.  YSlow includes (a version of) JSLint, which Douglas Crockford politely informed me might help debug my aforementioned JSON code.  Unfortunately, my initial tests were negative: JSLint didn’t barf on my bad test JSON returned via XHR; Firebug threw the same exception as before; Firebug continued to happily deconstruct the improperly-formatted object as if it were OK.  Hmm.  Maybe I’m missing something obvious.  The only JSLint errors I see are, ironically enough, in the JQuery core library and — *zing*! Douglas’ own json.js file.

Even if JSLint is inconclusive, YSlow does appear to have a lot of valuable performance-assessment information, which is why it was mentioned on the STS list.  So for that reason alone I’m going to start using it.  I think the simple grading scheme is a bit restrictive — why use a CDN if you don’t have the traffic to support the costs? — but it’s meant to be a guess and a guide, not a thorough analysis.