detect-newline 
Detect the dominant newline character of a string
Install
$ npm install --save detect-newline
Usage
const detectNewline = require('detect-newline');
detectNewline('foo\nbar\nbaz\r\n');
//=> '\n'
API
detectNewline(input)
Returns detected newline or null when no newline character is found.
detectNewline.graceful(input)
Returns detected newline or \n when no newline character is found.
Related
- detect-newline-cli - CLI for this module
- detect-indent - Detect the indentation of code
License
MIT © Sindre Sorhus