jQueryのajaxが，HTTPステータスコードの何番がsuccessで，何番がerrorなのか調べました

jQueryのajax関数は結果によってsuccessやerrorをcallbackしてくれます．
しかし，400番台や500番台はエラーだろうと予想できますが，300番台など分からなかったので調べてました．
WikipediaのHTTPステータスコードの一覧に乗っているステータスコードを試しました．
http://ja.wikipedia.org/wiki/HTTP%E3%82%B9%E3%83%86%E3%83%BC%E3%82%BF%E3%82%B9%E3%82%B3%E3%83%BC%E3%83%89

これが結果です．

100 is error
101 is error
102 is error
200 is success
201 is success
202 is success
203 is success
204 is success
205 is success
206 is success
207 is success
226 is success
300 is error
301 is error
302 is error
303 is error
304 is success
305 is error
306 is error
307 is error
400 is error
401 is error
402 is error
403 is error
404 is error
405 is error
406 is error
407 is error
408 is error
409 is error
410 is error
411 is error
412 is error
413 is error
414 is error
415 is error
416 is error
417 is error
418 is error
422 is error
423 is error
424 is error
425 is error
500 is error
501 is error
502 is error
503 is error
504 is error
505 is error
506 is error
507 is error
508 is error
509 is error
510 is error

304だけ300番台なのにsuccessでした．

続きは検証に使用したソースコードです．
CoffeeScriptです．実行する場合はJavaScriptにコンパイルしてNodeを使ってください．

# 検証するHTTPステータスコード
statusCodes = [].concat(
  [100..102]
  [200..207].concat [226]
  [300..307]
  [400..418].concat [422..424], [425]
  [500..510]
)

# Server
http = require 'http'
server = http.createServer (req, res) =>
  path = req.url.slice 1
  expectStatusCode = parseInt path
  res.writeHead expectStatusCode
  res.end()
server.listen 8080, 'localhost'

# Client
tryCount = 0
$ = require 'jQuery'
results = {}
for statusCode in statusCodes
  ((statusCode) => $.ajax
    url: 'http://localhost:8080/' + statusCode
    success: => results[statusCode] = 'success'
    error: => results[statusCode] = 'error'
    complete: =>
      tryCount++
      if tryCount is statusCodes.length
        for k, v of results
          console.log k + ' is ' + v
        server.close()
  ) statusCode