TypeScript - split string by new line character

In this article, we're going to have a look at the problem of how to split string to separate lines in TypeScript.

Note: by default in TypeScript \n newline character should be used, but modern applications exchange information with external endpoints that force programmers to deal with different cases - this article provides quick solutuioins for the problem.

Quick solution:

const text: string = 'line 1\nline 2';
const lines: string[] = text.split(/\r?\n/); // splits text by \r\n or \n

console.log(lines); // ['line 1', 'line 2']

Note: the above solution was inspired with new line characters that are used on MacOS, Linux and Windows.

Alternative quick solutions 

• It works on all operating systems:

const text: string =
  'line 1\r\n' + // \r\n - used as new line symbol
  'line 2\n' +   // \n   - used as new line symbol
  'line 3';

const lines: string[] = text.split(/\r\n|\n\r|\n|\r/); // split by:     \r\n  \n\r  \n  or  \r

console.log(lines); // [ 'line 1', 'line 2', 'line 3' ]

• It is an alternative approach that uses \R equivalent:

const text: string =
  'line 1\r\n' + // \r\n - used as new line symbol
  'line 2\n' +   // \n   - used as new line symbol
  'line 3';

const lines: string[] = text.split(/\u000D\u000A|[\u000A\u000B\u000C\u000D\u0085\u2028\u2029]/);

console.log(lines); // [ 'line 1', 'line 2', 'line 3' ]

Look at below problem description and examples to see how it works in practice.

1. Problem overview

Different operating systems have different newline symbols.

There are a few most commonly used new line separations:

Source: https://en.wikipedia.org/wiki/Newline

2. Problem solutions

2.1. Universal new lines splitting example

It is possible to propose some universal regular expression that lest to get a very good splitting result.

It is necessary to use \r\n|\n\r|\n|\r as a pattern.

Go to this article to see details and runnable example.

2.2. Alternative new lines splitting example using \R equivalent

Some modern regular expression implementations provide \R predefined character class,
e.g. Java, Notepad++, etc.

Most TypeScript engines don't support \R yet - so, it is required some trick.

Go to this article to see details and runnable example.

2.3. Microsoft Windows new lines splitting example

const text: string = 'line 1\r\n' + 'line 2\r\n' + 'line 3\r\n' + 'line 4\r\n' + 'line 5';

const lines: string[] = text.split('\r\n');

console.log(lines);

Output:

[ 'line 1', 'line 2', 'line 3', 'line 4', 'line 5' ]

Systems: Atari TOS, Microsoft Windows, DOS (MS-DOS, PC DOS, etc.), DEC TOPS-10, RT-11, CP/M, MP/M, OS/2, Symbian OS, Palm OS, Amstrad CPC, and most other early non-Unix and non-IBM operating systems.

2.4. Unix/Linux new lines splitting example

const text: string = 'line 1\n' + 'line 2\n' + 'line 3\n' + 'line 4\n' + 'line 5';

const lines: string[] = text.split('\n');

console.log(lines);

Output:

[ 'line 1', 'line 2', 'line 3', 'line 4', 'line 5' ]

Systems: Multics, Unix and Unix-like systems (Linux, macOS, FreeBSD, AIX, Xenix, etc.), BeOS, Amiga, RISC OS, and others.

2.5.  The classic Mac OS/OS-9 new lines splitting example

const text: string = 'line 1\r' + 'line 2\r' + 'line 3\r' + 'line 4\r' + 'line 5';

const lines: string[] = text.split('\r');

console.log(lines);

Output:

[ 'line 1', 'line 2', 'line 3', 'line 4', 'line 5' ]

Systems: Commodore 8-bit machines (C64, C128), Acorn BBC, ZX Spectrum, TRS-80, Apple II series, Oberon, the classic Mac OS, MIT Lisp Machine and OS-9.