Edge A/B

These primitives run A/B variant assignment at the edge, before your page renders, so the right variant is served without a client round trip. They are consent-free and deterministic. Source is in packages/cms/src/ab-edge and packages/cms/src/next.

`abTestMiddleware`

Next.js middleware that rewrites a request to the variant-coded route for a collection.

middleware.ts

import { abTestMiddleware } from '@createcms/core/next/middleware';

export const middleware = abTestMiddleware({
  collection: 'pages',
  cmsBaseUrl: process.env.CMS_BASE_URL,
});

Option	Type	Description
`collection`	`string`	The collection to resolve tests for (required).
`cmsBaseUrl`	`string`	Base URL of the CMS API.
`controlCode`	`string`	Code used for the control variant (default `control`).
`variantPrefix`	`string`	Route prefix for variant rewrites (default `/ab`).
`variantCookiePrefix`	`string`	Prefix for the variant cookie.
`variantCookieMaxAge`	`number`	Variant cookie lifetime in seconds.
`resolve`	`(request, path) => Promise<AbResolveResult>`	Custom resolver for running tests.

`createRevalidateHandler`

Next.js route handler for revalidation webhooks. It reads the secret from the x-revalidate-secret request header (constant-time compare, 401 on mismatch), then revalidates the event body's paths and tags.

import { createRevalidateHandler } from '@createcms/core/next';

export const POST = createRevalidateHandler({ secret: process.env.CMS_REVALIDATE_SECRET! });

The webhook caller must send the secret in the x-revalidate-secret header. See Use with Next.js for a caller example.

Edge primitives

Framework-agnostic building blocks from @createcms/core/ab-edge, for any edge runtime.

Export	Signature	Purpose
`CONTROL_CODE`	`'control'`	Sentinel code for the control variant.
`DEFAULT_VARIANT_PREFIX`	`'/ab'`	Default variant route prefix.
`variantRewritePath`	`(prefix, code, pathname) => string`	Build the variant-coded rewrite path.
`pickEdgeVariant`	`({ key, resolve }) => { branchId: string \| null }`	Pure bucketing: the branch to render, or null for control.
`generateEdgeVisitorId`	`() => string`	Edge-safe random visitor id.
`parseConsentCookie`	`(value) => boolean`	Whether analytics storage is granted.
`resolveVariant`	`(contextKey, testId, trafficPercentage, variants) => AssignmentResult`	Deterministic weighted variant assignment.
`decideEdgeVariant`	`({ pathname, resolve, assignedCode, controlCode?, variantPrefix? }) => { rewritePath, assignCode, testId }`	The full edge decision (the Next.js middleware is a thin adapter over it).

For the higher-level experiment plugin, see A/B testing.

abTestMiddleware

createRevalidateHandler

Edge primitives

On this page

`abTestMiddleware`

`createRevalidateHandler`