正则表达式：从字符到行尾的匹配，没有最后一个匹配组

Question

I want to extract the q param from some urls: 我想从一些网址中提取q参数：

.com/?gws_rd=ssl#q=test
.com/search?q=something+else&source=123

Here's a regex I came up with: q=(.*?)(&|$) . 这是我想出的一个正则表达式： q=(.*?)(&|$) 。 When & terminates, the results are: 当&终止时，结果为：

["q=test", "test", "&"]

otherwise, when it hits the end of line: 否则，当它到达行尾时：

["q=test", "test", ""]

This works but doesn't seem right. 这有效，但似乎不正确。

Is there a way to not include the last match group at all, since I'm not interested in it? 因为我对此不感兴趣，有没有办法完全不包括最后一场比赛？

Answer 1

Turn the last group into a positive lookahead assertion. 将最后一组转变为正面的前瞻性断言。

(?=&|$) asserts that the match must be followed by a & or end of the line anchor $ (?=&|$)断言必须在匹配项后加上&或行锚$结尾

q=(.*?)(?=&|$)

> ".com/?gws_rd=ssl#q=test".match(/q=(.*?)(?=&|$)/)
[ 'q=test',
  'test',
  index: 17,
  input: '.com/?gws_rd=ssl#q=test' ]

To print only the chars inside the captured group. 仅打印捕获的组中的字符。

> var s = ".com/?gws_rd=ssl#q=test"
undefined
> console.log(/q=(.*?)(?=&|$)/.exec(s)[1]);
test