--- title: Conditional response description: Return a response based on the incoming request's URL, HTTP method, User Agent, IP address, ASN or device type. image: https://developers.cloudflare.com/dev-products-preview.png --- > Documentation Index > Fetch the complete documentation index at: https://developers.cloudflare.com/workers/llms.txt > Use this file to discover all available pages before exploring further. [Skip to content](#%5Ftop) # Conditional response Return a response based on the incoming request's URL, HTTP method, User Agent, IP address, ASN or device type. If you want to get started quickly, click on the button below. [![Deploy to Cloudflare](https://deploy.workers.cloudflare.com/button)](https://deploy.workers.cloudflare.com/?url=https://github.com/cloudflare/docs-examples/tree/main/workers/conditional-response) This creates a repository in your GitHub account and deploys the application to Cloudflare Workers. * [ JavaScript ](#tab-panel-11954) * [ TypeScript ](#tab-panel-11955) * [ Python ](#tab-panel-11956) * [ Hono ](#tab-panel-11957) JavaScript ``` export default { async fetch(request) { const BLOCKED_HOSTNAMES = ["nope.mywebsite.com", "bye.website.com"]; // Return a new Response based on a URL's hostname const url = new URL(request.url); if (BLOCKED_HOSTNAMES.includes(url.hostname)) { return new Response("Blocked Host", { status: 403 }); } // Block paths ending in .doc or .xml based on the URL's file extension const forbiddenExtRegExp = new RegExp(/\.(doc|xml)$/); if (forbiddenExtRegExp.test(url.pathname)) { return new Response("Blocked Extension", { status: 403 }); } // On HTTP method if (request.method === "POST") { return new Response("Response for POST"); } // On User Agent const userAgent = request.headers.get("User-Agent") || ""; if (userAgent.includes("bot")) { return new Response("Block User Agent containing bot", { status: 403 }); } // On Client's IP address const clientIP = request.headers.get("CF-Connecting-IP"); if (clientIP === "1.2.3.4") { return new Response("Block the IP 1.2.3.4", { status: 403 }); } // On ASN if (request.cf && request.cf.asn == 64512) { return new Response("Block the ASN 64512 response"); } // On Device Type // Requires Enterprise "CF-Device-Type Header" zone setting or // Page Rule with "Cache By Device Type" setting applied. const device = request.headers.get("CF-Device-Type"); if (device === "mobile") { return Response.redirect("https://mobile.example.com"); } console.error( "Getting Client's IP address, device type, and ASN are not supported in playground. Must test on a live worker", ); return fetch(request); },}; ``` TypeScript ``` export default { async fetch(request): Promise { const BLOCKED_HOSTNAMES = ["nope.mywebsite.com", "bye.website.com"]; // Return a new Response based on a URL's hostname const url = new URL(request.url); if (BLOCKED_HOSTNAMES.includes(url.hostname)) { return new Response("Blocked Host", { status: 403 }); } // Block paths ending in .doc or .xml based on the URL's file extension const forbiddenExtRegExp = new RegExp(/\.(doc|xml)$/); if (forbiddenExtRegExp.test(url.pathname)) { return new Response("Blocked Extension", { status: 403 }); } // On HTTP method if (request.method === "POST") { return new Response("Response for POST"); } // On User Agent const userAgent = request.headers.get("User-Agent") || ""; if (userAgent.includes("bot")) { return new Response("Block User Agent containing bot", { status: 403 }); } // On Client's IP address const clientIP = request.headers.get("CF-Connecting-IP"); if (clientIP === "1.2.3.4") { return new Response("Block the IP 1.2.3.4", { status: 403 }); } // On ASN if (request.cf && request.cf.asn == 64512) { return new Response("Block the ASN 64512 response"); } // On Device Type // Requires Enterprise "CF-Device-Type Header" zone setting or // Page Rule with "Cache By Device Type" setting applied. const device = request.headers.get("CF-Device-Type"); if (device === "mobile") { return Response.redirect("https://mobile.example.com"); } console.error( "Getting Client's IP address, device type, and ASN are not supported in playground. Must test on a live worker", ); return fetch(request); },} satisfies ExportedHandler; ``` Python ``` import refrom workers import WorkerEntrypoint, Response, fetchfrom urllib.parse import urlparse class Default(WorkerEntrypoint): async def fetch(self, request): blocked_hostnames = ["nope.mywebsite.com", "bye.website.com"] url = urlparse(request.url) # Block on hostname if url.hostname in blocked_hostnames: return Response("Blocked Host", status=403) # On paths ending in .doc or .xml if re.search(r'\.(doc|xml)$', url.path): return Response("Blocked Extension", status=403) # On HTTP method if "POST" in request.method: return Response("Response for POST") # On User Agent user_agent = request.headers["User-Agent"] or "" if "bot" in user_agent: return Response("Block User Agent containing bot", status=403) # On Client's IP address client_ip = request.headers["CF-Connecting-IP"] if client_ip == "1.2.3.4": return Response("Block the IP 1.2.3.4", status=403) # On ASN if request.cf and request.cf.asn == 64512: return Response("Block the ASN 64512 response") # On Device Type # Requires Enterprise "CF-Device-Type Header" zone setting or # Page Rule with "Cache By Device Type" setting applied. device = request.headers["CF-Device-Type"] if device == "mobile": return Response.redirect("https://mobile.example.com") return fetch(request) ``` TypeScript ``` import { Hono } from "hono";import { HTTPException } from "hono/http-exception"; const app = new Hono(); // Middleware to handle all conditions before reaching the main handlerapp.use("*", async (c, next) => { const request = c.req.raw; const BLOCKED_HOSTNAMES = ["nope.mywebsite.com", "bye.website.com"]; const hostname = new URL(c.req.url)?.hostname; // Return a new Response based on a URL's hostname if (BLOCKED_HOSTNAMES.includes(hostname)) { return c.text("Blocked Host", 403); } // Block paths ending in .doc or .xml based on the URL's file extension const forbiddenExtRegExp = new RegExp(/\.(doc|xml)$/); if (forbiddenExtRegExp.test(c.req.pathname)) { return c.text("Blocked Extension", 403); } // On User Agent const userAgent = c.req.header("User-Agent") || ""; if (userAgent.includes("bot")) { return c.text("Block User Agent containing bot", 403); } // On Client's IP address const clientIP = c.req.header("CF-Connecting-IP"); if (clientIP === "1.2.3.4") { return c.text("Block the IP 1.2.3.4", 403); } // On ASN if (request.cf && request.cf.asn === 64512) { return c.text("Block the ASN 64512 response"); } // On Device Type // Requires Enterprise "CF-Device-Type Header" zone setting or // Page Rule with "Cache By Device Type" setting applied. const device = c.req.header("CF-Device-Type"); if (device === "mobile") { return c.redirect("https://mobile.example.com"); } // Continue to the next handler await next();}); // Handle POST requests differentlyapp.post("*", (c) => { return c.text("Response for POST");}); // Default handler for other methodsapp.get("*", async (c) => { console.error( "Getting Client's IP address, device type, and ASN are not supported in playground. Must test on a live worker", ); // Fetch the original request return fetch(c.req.raw);}); export default app; ``` ```json {"@context":"https://schema.org","@type":"TechArticle","@id":"https://developers.cloudflare.com/workers/examples/conditional-response/#page","headline":"Conditional response ยท Cloudflare Workers docs","description":"Return a response based on the incoming request's URL, HTTP method, User Agent, IP address, ASN or device type.","url":"https://developers.cloudflare.com/workers/examples/conditional-response/","inLanguage":"en","image":"https://developers.cloudflare.com/dev-products-preview.png","dateModified":"2026-04-23","publisher":{"@type":"Organization","name":"Cloudflare","url":"https://www.cloudflare.com/"},"isPartOf":{"@type":"WebSite","@id":"https://developers.cloudflare.com/#website","name":"Cloudflare Docs","url":"https://developers.cloudflare.com/"},"keywords":["Middleware","JavaScript","TypeScript","Python"]} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/directory/","name":"Directory"}},{"@type":"ListItem","position":2,"item":{"@id":"/workers/","name":"Workers"}},{"@type":"ListItem","position":3,"item":{"@id":"/workers/examples/","name":"Examples"}},{"@type":"ListItem","position":4,"item":{"@id":"/workers/examples/conditional-response/","name":"Conditional response"}}]} ```