带有捕获括号的JavaScript正则表达式 [英] JavaScript regular expression with capturing parentheses

问题描述

我有这一段：

<p>FIRST SECOND THIRD</p>

我希望在SPAN中包装第二个单词，如下所示：

and I want to wrap the second word in a SPAN like so:

<p>FIRST <span>SECOND</span> THIRD</p>

如果我这样做：

text.replace(/\s(\w+)\s/, '<span>$1</span>');

单词之前和之后的空格字符消失。为什么？我究竟做错了什么？我想 / \（（\ w +）\ s / 捕获单词而不是空格。

the space characters before and after the word disappear. Why? What am I doing wrong? I thought /\s(\w+)\s/ captures the word but not the spaces.

见这里： http://jsfiddle.net/simevidas/TpTzV/

推荐答案

空格被剥离，因为它们是整场比赛的一部分。捕获是记住通过反向引用替换回替换字符串的内容。

The spaces are stripped away because they're part of the entire match. The capture is what it remembers to substitute back into the replacement string via backreferences.

如果JavaScript支持前瞻和后瞻断言，你可以这样做：

If JavaScript supported both lookahead and lookbehind assertions you could do this:

text.replace(/(?<\s)(\w+)(?=\s)/, '<span>$1</span>');

但它没有，所以你可以尝试捕捉空格（与你的单词分开）包装）并将它们放回去：

But it doesn't, so you can try capturing the spaces (separately from the word you're wrapping) and putting them back in instead:

text.replace(/(\s)(\w+)(\s)/, '$1<span>$2</span>$3');

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