What is the JavaScript string newline character?

Question

Is \n the universal newline character sequence in JavaScript for all platforms? If not, how do I determine the character for the current environment?

I'm not asking about the HTML newline element (<BR/>). I'm asking about the newline character sequence used within JavaScript strings.

I have a multiline input control where the user is expected to enter a newline separated list. I need to parse the list by first splitting the string on newlines. — Landon Kuhn
– Landon Kuhn, Commented Jul 20, 2009 at 20:41
@landon9720: For my multiline input controls, I have a getValue function that takes the value and returns value.replace(/\r\n/g,'\n') - just to keep the output consistent across browsers/platforms. — Roy Tinker
– Roy Tinker, Commented Mar 8, 2012 at 17:16
Good question especially for those who are new to programming! Outside of HTML and in JavaScript it is good to know how to break to the next/new line. — Eric Bishard
– Eric Bishard, Commented May 11, 2015 at 19:57
I have used this in my console and got 2 different results. var a = "Hello"; var b = "world"; When I am trying to show this like a + "\n" + b; it gives me the output as Hello\nworld but if I put it in the console like console.log(a+"\n"+b); it gives the output as Hello and world in 2 different lines. — Ajish Kumar
– Ajish Kumar, Commented Jun 29, 2022 at 18:16

mercator · Accepted Answer · 2017-11-03 12:05:43Z

398

I've just tested a few browsers using this silly bit of JavaScript:

function log_newline(msg, test_value) {
  if (!test_value) { 
    test_value = document.getElementById('test').value;
  }
  console.log(msg + ': ' + (test_value.match(/\r/) ? 'CR' : '')
              + ' ' + (test_value.match(/\n/) ? 'LF' : ''));
}

log_newline('HTML source');
log_newline('JS string', "foo\nbar");
log_newline('JS template literal', `bar
baz`);

<textarea id="test" name="test">

</textarea>

IE8 and Opera 9 on Windows use \r\n. All the other browsers I tested (Safari 4 and Firefox 3.5 on Windows, and Firefox 3.0 on Linux) use \n. They can all handle \n just fine when setting the value, though IE and Opera will convert that back to \r\n again internally. There's a SitePoint article with some more details called Line endings in Javascript.

Note also that this is independent of the actual line endings in the HTML file itself (both \n and \r\n give the same results).

When submitting a form, all browsers canonicalize newlines to %0D%0A in URL encoding. To see that, load e.g. data:text/html,<form><textarea name="foo">foo%0abar</textarea><input type="submit"></form> and press the submit button. (Some browsers block the load of the submitted page, but you can see the URL-encoded form values in the console.)

I don't think you really need to do much of any determining, though. If you just want to split the text on newlines, you could do something like this:

lines = foo.value.split(/\r\n|\r|\n/g);

edited Nov 3, 2017 at 12:05

answered Jul 20, 2009 at 22:46

mercator

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5 Comments

AdrianoFerrari Over a year ago

Worked for me, had to use global flag though: /\r\n|\r|\n/g

mercator Over a year ago

@Edson and wrong, since it will treat \r\n as two newlines instead of one. If you want short, /\r?\n/g will probably do (who still uses Mac OS 9 anyway?).

cbmanica Over a year ago

Given that the SitePoint article is from 2004, the information there may not be relevant to current JS implementations.

Wilt Over a year ago

Match is supposedly much faster than split: jsperf.com/regex-split-vs-match

Ilya Loskutov Over a year ago

Does it mean a string can have different lengths in different browsers/systems depending on using CRLF vs CR for line breaks?

Sinan Taifour · Accepted Answer · 2009-07-20 20:09:33Z

94

Yes, it is universal.

Although '\n' is the universal newline characters, you have to keep in mind that, depending on your input, new line characters might be preceded by carriage return characters ('\r').

answered Jul 20, 2009 at 20:09

Sinan Taifour

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5 Comments

mercator Over a year ago

\n is the universal line feed character (LF). The exact newline byte sequence depends on the platform (\r\n, \n, or \r: en.wikipedia.org/wiki/Newline). And that's the question landon is asking. You're contradicting yourself when you first say it's the universal newline character, and then say it may be preceded by a CR. Which one is it?

GolezTrol Over a year ago

\n is the newline(line feed) character, even if it is preceded by a carriage return. CR should never be used on its own, although most Windows apis and apps will parse it as a newline. LF works just as well in Windows too. CR is just an artifact from the time when computers were merely electronic typewriters.

Dan Bechard Over a year ago

@GolezTrol There are valid reasons to use CR on its own. For instance, returning to the beginning of the line in a console window in order to overwrite the line, without moving to the next line. This is often used to write changing percent progress indicators in command line utilities.

GolezTrol Over a year ago

@Dan Thanks for the feedback. Of course, I should never have said "never", because there are indeed applications for a CR on its own. But the question is about Javascript not about command line utilities. Of course there may be a script running in CLI mode (although I don't know if CR will work like you said then), and you may even use Javascript to generate a script which is run in the command line. Those are possible exceptions to the rule, but in the context of the question they seem not to apply. Nevertheless, thanks for mentioning it.

sergiol Over a year ago

~preceded~ => preceded or succeeded

Quincy · Accepted Answer · 2012-01-21 20:32:53Z

62

It might be easiest to just handle all cases of the new line character instead of checking which case then applying it. For example, if you need to replace the newline then do the following:

htmlstring = stringContainingNewLines.replace(/(\r\n|\n|\r)/gm, "<br>");

answered Jan 21, 2012 at 20:32

Quincy

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1 Comment

EvilDr Over a year ago

Superb. Works great in later versions FF and IE (not tested older versions though)

Peter Mortensen · Accepted Answer · 2021-11-05 15:10:10Z

28

Yes, use \n, unless you are generating HTML code, in which case you want to use <br />.

edited Nov 5, 2021 at 15:10

Peter Mortensen

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answered Jul 20, 2009 at 20:11

Finer Recliner

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Comments

uzluisf · Accepted Answer · 2023-04-28 23:32:13Z

19

With ES6, you can use backtick quotes (``), which is below the Esc button on any US layout keyboard with size 75% or greater. So you can write something like this:

var text = `fjskdfjslfjsl
skfjslfkjsldfjslfjs
jfsfkjslfsljs`;

edited Apr 28, 2023 at 23:32

uzluisf

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answered May 26, 2017 at 12:46

Bogdan Surai

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5 Comments

Metehan Gülaç Over a year ago

perfect suggestion.

Peter Mortensen Over a year ago

On what keyboard layout? What particular keyboard?

CLS Over a year ago

@PeterMortensen Backtick's ascii code is 96, so You can type it by Alt+96 (on the keypad). It's between Esc and Tab on US keyboard layout. It's on AltGr+7 on Hungarian layout.

Timo Over a year ago

I needed span.style.whiteSpace = 'pre-wrap' to make it work. instead of var text=.. I have document.getElementById('span1').textContent=...text in backticks

Timo Over a year ago

When using innerHTML instead of textContent I can use html formatting and do not need whiteSpace together with your solution. So this is the trick.

Peter Mortensen · Accepted Answer · 2021-11-05 16:25:05Z

17

In an email link function, I use "%0D%0A":

function sendMail() {
    var bodydata="Before "+ "%0D%0A";
        bodydata+="After"

    var MailMSG = "mailto:[email protected]"
             + "[email protected]"
             + "&subject=subject"
             + "&body=" + bodydata;
    window.location.href = MailMSG;
}

HTML

<a href="#" onClick="sendMail()">Contact Us</a>

edited Nov 5, 2021 at 16:25

Peter Mortensen

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answered Oct 10, 2012 at 6:27

ISCI

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1 Comment

Nilay Mehta Over a year ago

any one know this type of code for tab key? i am tried "%0D%09" but not working.

Vitalii Fedorenko · Accepted Answer · 2012-02-01 00:34:49Z

8

Get a line separator for the current browser:

function getLineSeparator() {
  var textarea = document.createElement("textarea");
  textarea.value = "\n"; 
  return textarea.value;
}

edited Feb 1, 2012 at 0:34

answered Dec 19, 2011 at 3:40

Vitalii Fedorenko

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1 Comment

user890167 Over a year ago

Will using JSON.stringify on the result change the character? If I try to view the result in an alert() call it doesn't show me the character unless I stringify it first (not that the char needs to be human readable to be effective, of course)

JayCrossler · Accepted Answer · 2013-04-07 23:44:34Z

4

A note - when using ExtendScript JavaScript (the Adobe Scripting language used in applications like Photoshop CS3+), the character to use is "\r". "\n" will be interpreted as a font character, and many fonts will thus have a block character instead.

For example (to select a layer named 'Note' and add line feeds after all periods):

var layerText = app.activeDocument.artLayers.getByName('Note').textItem.contents;
layerText = layerText.replace(/\. /g,".\r");

answered Apr 7, 2013 at 23:44

JayCrossler

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1 Comment

Jake Stoeffler Over a year ago

Was trying to figure out why \n and <br/> weren't working in my Photoshop script... Thanks!

Peter Mortensen · Accepted Answer · 2021-11-05 16:42:49Z

3

printAccountSummary: function()
    {return "Welcome!" + "\n" + "Your balance is currently $1000 and your interest rate is 1%."}
};
console.log(savingsAccount.printAccountSummary()); // Method

Prints:

Welcome!
Your balance is currently $1000 and your interest rate is 1%.

edited Nov 5, 2021 at 16:42

Peter Mortensen

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answered May 17, 2018 at 2:59

Barbs G

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Comments

Oralet · Accepted Answer · 2011-02-02 14:45:14Z

1

I had the problem of expressing newline with \n or \r\n.
Magically the character \r which is used for carriage return worked for me like a newline.
So in some cases, it is useful to consider \r too.

edited Feb 2, 2011 at 14:45

answered Feb 2, 2011 at 14:01

Oralet

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1 Comment

CodeBrauer Over a year ago

This happens if your string has the ISO-8859-1 charset

Peter Mortensen · Accepted Answer · 2021-11-05 15:11:17Z

1

I believe it is -- when you are working with JavaScript strings.

If you are generating HTML, though, you will have to use <br /> tags (not \n, as you're not dealing with JavaScript any more).

edited Nov 5, 2021 at 15:11

Peter Mortensen

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answered Jul 20, 2009 at 20:12

Pascal MARTIN

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Comments

Peter Mortensen · Accepted Answer · 2021-11-05 16:45:00Z

0

A practical observation... In my Node.js script I have the following function:

function writeToLogFile (message) {
    fs.appendFile('myserverlog.txt', Date() + " " + message + "\r\n", function (err) {
        if (err) 
            throw err;
    });
}

First, I had only "\n", but I noticed that when I open the log file in Notepad, it shows all entries on the same line. Notepad++, on the other hand, shows the entries each on their own line. After changing the code to "\r\n", even Notepad shows every entry on its own line.

edited Nov 5, 2021 at 16:45

Peter Mortensen

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answered Jul 11, 2019 at 13:37

user11717468

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1 Comment

Peter Mortensen Over a year ago

On Windows, presumably.

Peter Mortensen · Accepted Answer · 2021-11-05 15:12:33Z

-3

The \n is just fine for all cases I've encountered. If you are working with web, use \n and don't worry about it (unless you have had any newline-related issues).

edited Nov 5, 2021 at 15:12

Peter Mortensen

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answered Sep 11, 2009 at 14:53

zzandy

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Comments

Peter Mortensen · Accepted Answer · 2021-11-05 16:27:37Z

-15

You can use <br/> and the document.write/ and document.writeln one.

edited Nov 5, 2021 at 16:27

Peter Mortensen

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answered Apr 16, 2013 at 23:34

omari Powell

1

1 Comment

Leigh Over a year ago

Please re-read the question. It specifically says he is not asking about <br>

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