如何编写JavaScript正则：匹配首尾固定且中间不含指定字符串

Got it, let's sort out this regex problem. Your original pattern /con\/.+\/top/ works for the basic structure, but it doesn't account for excluding strings that have "pop" in the middle—since .+ greedily matches everything up to the final /top, including any instances of "pop" along the way.

The Fixed Regex #

Here's the adjusted pattern that will exclude any string with "pop" in the middle section:

const regex = /con\/(?:(?!pop).)*\/top/;

Breaking Down the Pattern #

Let's walk through each part to understand how it works:

• con\/: Matches the required starting sequence con/ (we escape / with \/ because it's a special character in regex syntax).
• (?:(?!pop).)*: This is the key part that blocks "pop":
  • (?!pop) is a negative lookahead assertion—it checks that the next three characters are not pop before allowing any character to be matched.
  • . matches any single character (by default, this doesn't include newlines; if you need to match newlines, add the s flag at the end: /con\/(?:(?!pop).)*\/top/s).
  • * repeats this check for every character in the middle section, ensuring "pop" never appears anywhere between con/ and /top.
  • ?: makes this a non-capturing group, so it doesn't store unnecessary match data.
• \/top: Matches the required ending sequence /top.

Test Cases #

Let's verify with your example and other scenarios:

• Matches (valid strings):
  • con/abc/def/top
  • con/single-segment/top
  • con/no-pop-here/top
• Does NOT match (invalid strings):
  • con/bottom/pop/down/top (your original test case with "pop" in the middle)
  • con/pop/top (directly has "pop" after con/)
  • con/abcpopdef/top (has "pop" embedded in a segment)

If you need case-insensitive matching, just add the i flag at the end, like /con\/(?:(?!pop).)*\/top/i.

内容的提问来源于stack exchange，提问作者Selvakumar