how to write a regex to match a “\n” which is not followed another “\n”?

Question

I want to replace "\\n" with ""(empty string) only when "\\n" is not followed by another "\\n".

var text  = "abcdefg
             abcdefg

             1234556
             1234556

             ABCDEFG
             ABCDEFG";

So, if I have a string as the above, I want to make it like this after replacing "\\n"s.

"abcdefgabcdefg

 12345561234556

 ABCDEFGABCDEFG";

But, I can't find out how to write a regex to match a "\\n" that is not followed another "\\n".

These are what I tried, but these match both "\\n" and "\\n\\n".

var pattern1 = new RegExp("\\n{1}");
var pattern2 = new RegExp("\\n(?!\\n)");

Could anyone please help me to write a regex in this case?

Thanks!

Answer 1

You can match the following:

[^\\\\n](\\\\n)[^\\\\n]

Demo: http://regex101.com/r/eP9xD1

Answer 2

You can use /([^\\n])\\n([^\\n])/g and replace it with \\1\\2 .

Usage :

> str = 'abcdefg\nabcdefg\n\n1234556\n1234556\n\nABCDEFG\nABCDEFG';
> str.replace(/([^\n])\n([^\n])/g, '\1\2');
  "abcdefbcdefg

  123455234556

  ABCDEFBCDEFG"

REGEX DEMO

FIDDLE

Answer 3

您可以使用否定前瞻匹配\\n ，然后再匹配另一个\\n ：

\n(?!\n)