Javascript 正则表达式负向后视

问题描述

我正在尝试找出在 javascript 中执行此操作的正确正则表达式.在 pcre 中，这正是我想要的:

I'm trying to figure out the correct regex to do this in javascript. In pcre, this does exactly what I want:

/^.*(?<!\/)kb([0-9]+).*$/im

目标:

• 如果我有一个不带正斜杠前缀的值，例如 KB12345，它将匹配其中的数字.
• 如果该值以正斜杠为前缀，它将不匹配，例如:http://someurl.com/info/KB12345

• If I have a value that isn't prefixed with a forward-slash, e.g KB12345, it'll match the number within.
• If that value is prefixed with a forward-slash it won't match, e.g:http://someurl.com/info/KB12345

然而，虽然它在 pcre 中有效，但由于否定的语法，它在 javascript 中不起作用:

However it looks like while this works in pcre, it won't work in javascript due to the syntax of the negation:

(?<!\/)

我一直试图在 regex101 中解决这个问题，但还没有运气.关于 javascript 中的纯正则表达式等价物的任何想法或建议是什么?

I've been trying to figure this out in regex101 but no luck yet. Any ideas or suggestions on what the pure-regex equivalent in javascript is?

我看到有一个负面的展望，但我似乎无法弄清楚:

I saw there's a negative look-ahead, but I can't seem to figure it out:

/^.*(?!\/KB)kb([0-9]+).*$/im

推荐答案

使用以下正则表达式匹配正确的文本:

Use the following regex to match the right text:

/(?:^|[^\/])kb([0-9]+)/i

查看正则表达式演示

详情:

• (?:^|[^\/]) - 字符串或 / 以外的字符的开头
• kb - 文字字符串 kb
• ([0-9]+) - 第 1 组匹配 1 个或多个数字.

• (?:^|[^\/]) - start of string or a char other than /
• kb - a literal string kb
• ([0-9]+) - Group 1 matching 1 or more digits.

var ss = ["If I have a value that isn't prefixed with a forward-slash, e.g KB12345, it'll match the number within.","If that value is prefixed with a forward-slash it won't match, e.g: http://someurl.com/info/KB12345"];
var rx = /(?:^|[^\/])kb([0-9]+)/i;
for (var s of ss) {
 var m = s.match(rx);
 if (m) { console.log(m[1], "found in '"+s+"'") };
}

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