此javascript正则表达式会替换空白吗？

Question

我正在浏览Twitter引导程序的代码，并且在此代码段中出现了几次昏迷。

href.replace(/.*(?=#[^\s]+$)/, '') //strip for ie7

正则表达式是我的盲点，我无法弄清它们中的大多数。 替代什么？ ＃后面是否有空格？

边注。 谁能推荐正则表达式学费的好来源？

Answer 1

它在寻找什么：

.*     # any number of characters (optional)
(?=    # open a lookahead
#      # find a hash tag
[^\s]+ # at least one non-whitespace character
$      # end of line
)      # close the lookahead

因此，例如，它与哈希标签之前的内容匹配：

replace this!#foobar   <-- matches: replace this!
hello world#goodbye    <-- matches: hello world
no match here !        <-- doesn't match anything because there is no hash
what?#                 <-- does not match because there is nothing after the hash
what?# asd             <-- does not match because there is a whitespace-character