Replace multiple blank lines in text using Javascript

Question

Hopefully a simple question.

If I have text like this:

Orange
Apples


Melons

Bananas

...how can I replace all occurrences of multiple blank lines with single blank lines, ending up with this:

Orange
Apples

Melons

Bananas

Fiddle: http://jsfiddle.net/Jq4pT/ Need to remove multiple blank lines from the first box's input before inserting into the second.

I've found this link, but am not sure how to use that regular expression in Javascript?

Thanks.

Answer 1

This is an old question, but I don't care, it comes up first in Google search.

You can do this with the following code:

var EOL = string.match(/\r\n/gm)?"\r\n":"\n";
var regExp = new RegExp("("+EOL+"){3,}", "gm");
string = string.replace(regExp, EOL+EOL);

• First it determines the endline char to use in Regex
• Regex looks for EOL chars being repeated 3 or more times, and replaces them with 2 EOL chars.
• Using g modifier to replace all occurrences
• Using m modifier to apply regex to the whole multi-line string, instead of per line.

Answer 2

Just use it like this:

var inputString = '...';
var outputString = inputString.replace(/^(\s*\r\n){2,}/, "\r\n")