A/B testing with middleware
Set up an A/B test by controlling what page is served based on cookies. This version supports passing the request through to test and control on the origin.
const cookieName = "ab-test-cookie"const newHomepagePathName = "/test"
const abTest = async (context) => { const url = new URL(context.request.url) // if homepage if (url.pathname === "/") { // if cookie ab-test-cookie=new then change the request to go to /test // if no cookie set, pass x% of traffic and set a cookie value to "current" or "new"
let cookie = request.headers.get("cookie") // is cookie set? if (cookie && cookie.includes(`${cookieName}=new`)) { // pass the request to /test url.pathname = newHomepagePathName return context.env.ASSETS.fetch(url) } else { const percentage = Math.floor(Math.random() * 100) let version = "current" // default version // change pathname and version name for 50% of traffic if (percentage < 50) { url.pathname = newHomepagePathName version = "new" } // get the static file from ASSETS, and attach a cookie const asset = await context.env.ASSETS.fetch(url) let response = new Response(asset.body, asset) response.headers.append("Set-Cookie", `${cookieName}=${version}; path=/`) return response } } return context.next()};
export const onRequest = [abTest];