javascript 使用正则表达式仅用 JS 替换最后一次出现的模式
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Using regex to replace only the last occurrence of a pattern with JS
提问by AriehGlazer
I have a case where I'm trying to replace a certain pattern with another. My problem is that I need to only replace the last occurrence of that pattern, not all of them. I've found this question:
我有一个案例，我试图用另一种模式替换某个模式。我的问题是我只需要替换该模式的最后一次出现，而不是全部。我发现了这个问题：
How to replace last occurrence of characters in a string using javascript
But it doesn't fit my needs. As a background, I will say that I am trying to replace a CSS rule, but for the current example lets look at this text:
但它不符合我的需求。作为背景，我会说我正在尝试替换 CSS 规则，但对于当前示例，让我们看看这段文字：
abcd:bka:
bbb:aad:
accx:aaa:
bbb:a0d:
cczc:aaa:
lets say I only want to replace the value of bbb. My current rule will be
假设我只想替换 bbb 的值。我目前的规则是
text.replace(/(\s*bbb:)([^:]+)/,"aaa")
but it will only replace the first match, while I want it to replace the last one. My current pattern is actually more complex than this one, but I think the pseudo problem will suffice.
但它只会替换第一个匹配项，而我希望它替换最后一个匹配项。我目前的模式实际上比这个更复杂，但我认为伪问题就足够了。
回答by Tim Pietzcker
Try
尝试
text.replace(/(\s*bbb:)(?![\s\S]*bbb:)[^:]+/,"aaa")
The negative lookahead assertion makes sure that there is no further bbb:ahead in the text. The parentheses around [^:]+are unnecessary.
否定前瞻断言确保bbb:文本中没有进一步的内容。周围的括号[^:]+是不必要的。
Explanation:
解释：
(?! # Assert that it is impossible to match the following after the current position:
[\s\S]* # any number of characters including newlines
bbb: # the literal text bbb:
) # End of lookahead assertion
The [\s\S]workaround is necessary because JavaScript doesn't have an option to allow the dot to match newlines.
的[\s\S]，因为JavaScript没有一个选项，以使点以匹配新行的解决办法是必要的。
