index.js

'use strict';
const createHtmlElement = require('create-html-element');

// Capture the whole URL in group 1 to keep string.split() support
const urlRegex = () => (/((?:https?(?::\/\/))(?:www\.)?(?:[a-zA-Z\d-_.]+(?:(?:\.|@)[a-zA-Z\d]{2,})|localhost)(?:(?:[-a-zA-Z\d:%_+.~#!?&//=@]*)(?:[,](?![\s]))*)*)/g);

// Get <a> element as string
const linkify = (href, options) => createHtmlElement({
	name: 'a',
	attributes: Object.assign({href: ''}, options.attributes, {href}),
	text: typeof options.value === 'undefined' ? href : undefined,
	html: typeof options.value === 'undefined' ? undefined :
		(typeof options.value === 'function' ? options.value(href) : options.value)
});

// Get DOM node from HTML
const domify = html => document.createRange().createContextualFragment(html);

const getAsString = (input, options) => {
	return input.replace(urlRegex(), match => linkify(match, options));
};

const getAsDocumentFragment = (input, options) => {
	return input.split(urlRegex()).reduce((frag, text, index) => {
		if (index % 2) { // URLs are always in odd positions
			frag.appendChild(domify(linkify(text, options)));
		} else if (text.length > 0) {
			frag.appendChild(document.createTextNode(text));
		}

		return frag;
	}, document.createDocumentFragment());
};

module.exports = (input, options) => {
	options = Object.assign({
		attributes: {},
		type: 'string'
	}, options);

	if (options.type === 'string') {
		return getAsString(input, options);
	}

	if (options.type === 'dom') {
		return getAsDocumentFragment(input, options);
	}

	throw new Error('The type option must be either `dom` or `string`');
};