javascript, replace \n with \r\n

Question

I need to replace all \n with \r\n, but only if \n hasn't already \r previosly.
i.e.
Hello\nGreat\nWorld -> Hello\r\nGreat\r\nWorld
Hello\r\nGreat\r\nWorld -> Hello\r\nGreat\r\nWorld.

In Java i can do it in next way

"Hello\nGreat\nWorld".replaceAll("(?<!\r)\n", "\r\n");

But (?<!X) construct is absent in JS.
Any ideas, how can I do it in JS?

just replace all `\r\n` by `\n`, after that all `\n` by `\r\n`. No fancy regex needed. — Yoshi, Apr 23 '13 at 09:04
[Possible duplicate](http://stackoverflow.com/questions/7376238/javascript-regex-look-behind-alternative) — Florian F., Apr 23 '13 at 09:04

score 36 · Accepted Answer · answered Apr 23 '13 at 09:05

36

Simply make the \r an optional part of the match, then you can replace with impunity:

"Hello\r\nWorld\n".replace(/\r?\n/g, "\r\n")

answered Apr 23 '13 at 09:05

Jon

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@Jack: I saw all that and was currently thinking "that happens to me all the time too" :) – Jon Apr 23 '13 at 09:07

score 5 · Answer 2 · answered Apr 23 '13 at 09:06

5

str.replace('\r\n', '\n').replace('\n', '\r\n')

answered Apr 23 '13 at 09:06

RichieHindle

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javascript, replace \n with \r\n

2 Answers2