Cloudflare 301 redirect based on user agent.

worker.js

export default {
    async fetch(request) {
        const botUserAgents = new Map([
            [/botUserAgent1/i, "bot=bot1"],
            [/botUserAgent2/i, "bot=bot2"],
            [/botUserAgent3/i, "bot=bot3"]
        ]);

        const userAgent = request.headers.get('User-Agent');
        if (userAgent) {
            for (const [regex, utmParam] of botUserAgents) {
                if (regex.test(userAgent)) {
                    // Construct the new URL with the UTM parameter
                    const url = new URL(request.url);
                    const [key, value] = utmParam.split('=');
                    url.searchParams.set(key, value);

                    // Perform a 301 redirect
                    return Response.redirect(url.toString(), 301);
                }
            }
        }

        return fetch(request);
    },
};