detect-newline 
Detect the dominant newline character of a string
Install
$ npm install detect-newline
Usage
const detectNewline = require('detect-newline');
detectNewline('foo\nbar\nbaz\r\n');
//=> '\n'
API
detectNewline(string)
Returns the detected newline or undefined when no newline character is found.
detectNewline.graceful(unknown)
Returns the detected newline or \n when no newline character is found or the input is not a string.
Related
- detect-newline-cli - CLI for this module
- detect-indent - Detect the indentation of code
License
MIT © Sindre Sorhus