JavaScript RegExp Newline Metacharacter (\n)

What Is \n?

\n matches the line feed (LF) character (U+000A, ASCII 10) — the usual newline on Unix, Linux, and modern macOS. Use it to detect, split, or normalize line breaks in text.

\n    → line feed / newline (U+000A)
\r    → carriage return (different character)
\r\n  → Windows-style line ending (CR + LF)
\s    → any whitespace, including \n

"a\nb"           → two lines in a string
/\n/.test(...)   → true when LF is present
split(/\n/)      → break into lines

How to Use \n

Treat line feed as a concrete character — test for it, split on it, or normalize mixed endings.

1. Create or import text with newlines (string escape: "\n").
2. Use /\n/ with test, match, split, or replace.
3. Add the g flag when you need every newline, not just the first.
4. For Windows/legacy files, prefer /\r\n|\r|\n/ so CRLF is not split twice.

Pseudocode

pattern has "\n"
read next character ch from the string

if ch.codePoint === 0x000A:   // line feed
    accept match
else:
    fail this path

common actions:
  test(str)                 → true/false
  split(str)                → one entry per line
  replace(/\r\n|\r|\n/g)    → normalize endings

Cheat Sheet

Keep these facts handy when working with line breaks.

Live Preview

Run common \n operations on sample multiline text.

text = "two\nlines"
/\n/.test(text)
→ true

/* line feed (U+000A) is present */

JavaScript Examples

Short, copy-ready snippets. Open DevTools Console, or use Try It Yourself for a live editor.

console.log(/\n/.test("one line"));    // false
console.log(/\n/.test("two\nlines"));  // true
console.log(/\n/.test("a\r\nb"));      // true (CRLF includes LF)

false
true
true

const log = "INFO boot\nWARN slow\nERROR fail";

const lines = log.split(/\n/);
console.log(lines);
// ["INFO boot", "WARN slow", "ERROR fail"]

console.log(lines[1]); // "WARN slow"

["INFO boot", "WARN slow", "ERROR fail"]
WARN slow

const mixed = "a\r\nb\nc\rd";

const lines = mixed.split(/\r\n|\r|\n/);
console.log(lines); // ["a", "b", "c", "d"]

const normalized = mixed.replace(/\r\n|\r/g, "\n");
console.log(JSON.stringify(normalized));
// "a\nb\nc\nd"

["a", "b", "c", "d"]
"a\nb\nc\nd"

Performance Notes

Matching a single control character is cheap. Prefer the mixed alternation only when files may use CRLF or bare \r; otherwise /\n/ is enough.

Key Takeaways