worker.js

const original = new URL('https://foo.com/boo/bar/baz/boo?qux');
const kvData = {};

kvData.redirects = [
	{
		// expected result: https://foo.com/boo/baz/boo
		from: '^/(foo|boo)/bar/(.*)',
		to: '/$1/$2',
		status: 301,
		pathOnly: true,
	},
	{
		// expected result: https://www.foo.com/foo/bar/baz/boo?qux
		from: 'https://foo.com/(.*)',
		to: 'https://www.foo.com/$1',
		status: 302,
		pathOnly: false,
	},
]

function handleRedirects() {
	for (const redirect of kvData.redirects) {
		const stringToMatch = redirect.pathOnly ? original.pathname : original.href;
		const matches = stringToMatch.match(new RegExp(redirect.from));
	
		if (matches?.length) {
			const replaced = redirect.to.replace(new RegExp('\\$(\\d)', 'g'), function(match, index) {
				return matches[index]
			});
			
			const location = new URL(replaced, original);
			console.log(location);
			
			return new Response(null, {
				status: redirect.status,
				headers: {
					Location: location,
				},
			});
		}
	}
}

handleRedirects()