替换或删除第n个\\ n

Question

This is my string:

var ok = "\n\n33333333333\n\n\n";

How to replace the 4th occurence of '\\n' with ''? Or, how to remove the 4th occurence of '\\n'?

Answer 1

• find n-1 occurences and other characters.
• capture the submatch.
• find the next occurence.

• replace the entire match with the captured submatch, and the replacement character/string

  "AA33333333333AAA".replace(/((?:[^A]*A){3}[^A]*)A/,"$1k")

(with A and k insteead of \\n and "" so you can more clearly see the results)

Answer 2

Here's what, at least to me, is a fine readable solution:

var i = 0;
ok = ok.replace(/\n/g, function () {
  return ++i == 4 ? "" : "\n";
});

However, it might not win as far as performance is concerned.