javascript regex detect duplicate blank lines-CodePudding

I tried to detect duplicate blank lines with

\s*\n\n

but doesn't seem to work with

  test1
   
    
   
   test2
   test3
  test4

  test1
   
    
   
   test2
   test3
  test4

CodePudding user response：

As commented,

A simpler way would be /\n{2,}/ or /\n[^\S] /

you can try /\n[^\S]*\n/.

Idea is to check for new line, optionally followed by whitespace character followed by a new line.

CodePudding user response：

You can use

\n(?:[^\S\n]*\n)

See the regex demo. If there can be CRLF endings:

\r?\n(?:[^\S\n\r]*\r?\n)

Details:

\r? - an optional carriage return symbol
\n - a newline char
(?:[^\S\n]*\n) - one or more occurrences of
- [^\S\n]* - zero or more whitespace chars excluding newline char, and then
- \n - a newline char.