escape-string-regexp 
Escape RegExp special characters
Install
$ npm install --save escape-string-regexp
Usage
const escapeStringRegexp = require('escape-string-regexp');
const escapedString = escapeStringRegexp('how much $ for a unicorn?');
//=> 'how much \$ for a unicorn\?'
new RegExp(escapedString);
License
MIT © Sindre Sorhus