index.js

'use strict';

module.exports = url => {
	if (typeof url !== 'string') {
		throw new TypeError(`Expected a \`string\`, got \`${typeof url}\``);
	}

	// Don't match Windows paths `c:\`
	if (/^[a-zA-Z]:\\/.test(url)) {
		return false;
	}

	// Scheme: https://tools.ietf.org/html/rfc3986#section-3.1
	// Absolute URL: https://tools.ietf.org/html/rfc3986#section-4.3
	return /^[a-zA-Z][a-zA-Z\d+\-.]*:/.test(url);
};