javascript - 匹配给定的正则表达式，除非给定的单词存在(lookahead 或lookbehind)

Question

我正在使用 javascript 正则表达式来解析一系列 URL。我需要匹配 URL 中的数字(实际上更复杂，但我正在简化)，但只想匹配给定单词不在 URL 中的数字。

也就是说，我想排除其中包含“changelogs”一词的行，因此会捕获“1047”、“1048”、“1245” ' 和 '1049' 来自以下列表；

http://www.opera.com/docs/changelogs/unified/1215/
http://www.whatever.com/docs/changelogs/anythingelse/anything/1215/
http://www.blabblah/security/advisory/1047
http://booger/security/advisory/1048/
ftp://msn.global.whatever/somethingelse/1245
whatever/it/doesnt/matter/could/be/anything/i/still/want/this/number/1049/

我知道我需要某种环顾四周、向前看、向后看的方式，但我正在淘汰。这是我尝试过的最后一种模式；

(?!changelogs)(\d+)

Here is the regex101 sandbox I'm using .

此外，唯一匹配的是实际数字，这一点很重要。我不希望有任何其他内容匹配。

---

这是我的 .NET 代码的样子(注意“BulletinOrAdvisoryPattern”是有问题的正则表达式)...

Regex bulletinPattern = new Regex(@matchingDomain.Vendor.BulletinOrAdvisoryPattern, RegexOptions.IgnoreCase );
Match bulletinMatch = bulletinPattern.Match(referenceTitle);

                    if (bulletinMatch.Success)
                    {
                        //Found the bulletin ID in the NVD Reference Title 
                        return bulletinMatch.Value;
                    }

Answer 1

您需要的“丑陋”正则表达式是

(?<=http://www\.opera\.com\b(?!.*/changelogs(?:/|$))\S*)\d+

请参阅.NET regex demo

但是，您所需要的只是

var result = input.Contains("/changelogs/") ? "" : input.Trim('/').Split('/').LastOrDefault();

请参阅IDEONE C# demo :

var lst = new List<string>() {"http://w...content-available-to-author-only...a.com/docs/changelogs/unified/1215/",
    "http://w...content-available-to-author-only...a.com/docs/changelogs/anythingelse/anything/1215/",
    "http://w...content-available-to-author-only...a.com/security/advisory/1047",
    "http://w...content-available-to-author-only...a.com/security/advisory/1048/",
    "http://w...content-available-to-author-only...a.com/doesnt/matter/could/be/anything/1049/"};
lst.ForEach(m => Console.WriteLine(
        m.Contains("/changelogs/") ? "" : m.Trim('/').Split('/').LastOrDefault()
    ));

更新

您将语言从 C# 切换到 JavaScript，这极大地改变了情况，因为 JS 正则表达式引擎不支持lookbehind。

因此，您必须解决它，并且有一些方法可以模仿lookbehind，或者仅使用捕获机制。

如果您可以使用捕获，请尝试

/^(?!.*\/changelogs(?:\/|$)).*\/(\d+)/

请参阅regex demo

var re = /^(?!.*\/changelogs(?:\/|$)).*\/(\d+)/gmi; 
var str = 'http://www.opera.com/docs/changelogs/unified/1215/\nhttp://www.whatever.com/docs/changelogs/anythingelse/anything/1215/\nhttp://www.blabblah/security/advisory/1047\nhttp://booger/security/advisory/1048/\nftp://msn.global.whatever/somethingelse/1245\nwhatever/it/doesnt/matter/could/be/anything/i/still/want/this/number/1049/';
var res = [];
 
while ((m = re.exec(str)) !== null) {
  res.push(m[1]);
}
document.body.innerHTML = JSON.stringify(res, 0, 4);

或者，使用可选组(如果要替换):

var re = /(\/changelogs\/.*)?\/(\d+)/gi; 
var str = 'http://www.opera.com/docs/changelogs/unified/1215/\nhttp://www.whatever.com/docs/changelogs/anythingelse/anything/1215/\nhttp://www.blabblah/security/advisory/1047\nhttp://booger/security/advisory/1048/\nftp://msn.global.whatever/somethingelse/1245\nwhatever/it/doesnt/matter/could/be/anything/i/still/want/this/number/1049/';
var result = str.replace(re, function (m, g1, g2){
  return g1 ? m : "NEW_VAL";
});
document.body.innerHTML = result;