Question

How do I replace multiple \n‘s with just one? So if a user enters

blah 

blahdy blah



blah blah

I want it to end up looking like.

blah
blahdy blah
blah blah

I know I could loop through with a while() but would rather use a regular expression, since I believe it’s more efficient.

Answer 1

This worked for me:

string = string.replace(/\n+/g, '\n');

As others have said, it replaces each occurrence of one or more consecutive newline characters (\n+) with just one.

The g effects a “global” replace, meaning it replaces all matches in the string rather than just the first one.

Edit: If you want to take into account other operating systems’ line ending styles as well (e.g., \r\n), you could do a multi-step replace:

string = string.replace(/(\r\n)+/g, '\r\n') // for Windows
    .replace(/\r+/g, '\r')                  // for Mac OS 9 and prior
    .replace(/\n+/g, '\n');                 // for everything else

OR (thanks to Renesis for this idea):

string = string.replace(/(\r\n|\r|\n)+/g, '$1');

If you know in advance what sort of text you’re dealing with, the above is probably overkill as it carries am obvious performance cost.