如果之前的文本等于，则不替换(Not replace if the text before is equal to)

如果之前的文本等于，则不替换(Not replace if the text before is equal to)

以下是我的替换代码：

.replace(/java(script)/g,'$1')

所以"some javascript to replace"将"some script to replace"后成为"some script to replace" 。 我想要的是如果javascript以#开头，我不想用#script替换#script 。 所以结果

"some #javascript to replace"应该是"some #javascript to replace"

我应该使用什么样的正则表达式？

The following is my replacement code:

.replace(/java(script)/g,'$1')

So "some javascript to replace" will become "some script to replace" after replacement. What I want is if the javascript starts with #, I don't want to replace #javascript with #script. So the result of

"some #javascript to replace" should be "some #javascript to replace"

What regex should I use?

最满意答案

使用以下正则表达式替换：

var s = "some javascript #javascript to replace";
s = s.replace(/(^|[^#])java(script)/g,'$1$2');
console.log(s); 
  
 
 
 细节 ： 
 
 
  (^|[^#]) - 捕获组1匹配字符串的开头或除#以外的任何字符#  
  java - 一个文字char序列java  
  (script) - 捕获与文字字符序列script匹配的组2。  
 
 在替换模式中，捕获的部分将重新插入到生成的字符串中，只有在没有#前面并且后跟script才会有效地删除java 。 
Use the following regex replacement:
 
 
 
  
  
var s = "some javascript #javascript to replace";
s = s.replace(/(^|[^#])java(script)/g,'$1$2');
console.log(s); 
  
 
 
Details:
 
 
 (^|[^#]) - capturing group 1 matching either the start of string or any char other than # 
 java - a literal char sequence java 
 (script) - capturing group 2 matching a literal char sequence script. 
 
In the replacement pattern, the captured parts are re-inserted into the resulting string, effectively removing java only if not preceded with # and followed with script.