匹配两个不带括号的引号 [英] Match two quotes not preceded by opening bracket

问题描述

我需要一个正则表达式，匹配所有出现在引号(()之前的两个引号('').我对括号做了一个负面的展望，后跟了一个引号.但是为什么这不起作用:

I need a regex matching all occurrences of two quotes ('') not preceded by opening bracket ((). I did a negative lookahead for the bracket followed by a quote. But why is this not working:

/(?!\()''/g

例如使用该字符串

(''test''test

它应该匹配第二个匹配项，但不匹配第一个匹配项，但它匹配两个匹配项.

It should match the second occurrence but not the first one but it matches both.

当我使用完全相同的解决方案但检查换行而不是括号时，它工作正常:

When I use exactly the same solution but with check for new line instead of bracket it works fine:

/(?!^)''/g

使用此字符串:

''test''test

它仅按预期匹配第二次出现.

It matches as expected only second occurrence.

在此处

推荐答案

即使您需要处理连续双撇号，

var output = "''(''test'''''''test".replace(/(\()?''/g, function($0, $1){
	return $1 ? $0 : 'x';
});
document.body.innerHTML = output;

在这里，/(\()?''/g正则表达式搜索带(且不带(的所有匹配项，但是在replace回调方法内部，我们检查第1组匹配项.如果第1组匹配，并且不为空，则将整个匹配用作替换文本($0代表整个匹配值)，如果不匹配(在''之前没有()，则只需插入替换.

Here, the /(\()?''/g regex searches for all matches with the ( and without, but inside the replace callback method, we check for the Group 1 match. If Group 1 matched, and is not empty, we use the whole match as the replacement text ($0 stands for the whole match value) and if it is not (there is no ( before '') we just insert the replacement.

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