JavaScript RegExp：我可以获取最后匹配的索引或向后搜索/ RightToLeft吗？ [英] JavaScript RegExp: Can I get the last matched index or search backwards/RightToLeft?

问题描述

假设我有一个字符串

foo bar baz foo bar baz foo bar baz foo bar baz 

我想找到最后一次出现的酒吧，我该怎样才能有效地做到这一点？我需要循环添加匹配吗？在.NET中，我可以在JS中进行RightToLeft搜索，我想我不能？

I want to find for the last occurance of bar, how can I effectively do this? do I need to loop through add matches? In .NET I can do a RightToLeft search in JS, I guess I can't?

推荐答案

bar(?!.*bar)

会找到最后一个 bar in a string：

will find the last bar in a string:

bar   # Match bar
(?!   # but only if it's not followed by...
 .*   # zero or more characters
 bar  # literal bar
)     # end of lookahead

如果您的字符串可能包含换行符，请使用

If your string may contain newline characters, use

bar(?![\s\S]*bar)

。 [\\\\ S] 匹配任何字符，包括换行符。

instead. [\s\S] matches any character, including newlines.

例如：

match = subject.match(/bar(?![\s\S]*bar)/);
if (match != null) {
    // matched text: match[0]
    // match start: match.index
}

您可能还想用 \围绕搜索词（如果它们确实是由字母数字字符组成的单词） b 锚点以避免部分匹配。

You might also want to surround your search words (if they are indeed words composed of alphanumeric characters) with \b anchors to avoid partial matches.

\bbar\b(?![\s\S]*\bbar\b)

匹配单独的 bar 而不是中的栏 foobar ：

matches the solitary bar instead of the bar within foobar:

Don't match bar, do match bar, but not foobar!
  no match---^     match---^    no match---^

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