fix: Add more A/B testing examples

[arnavnagzirkar]

Summary

Issue #27 requests A/B testing examples for several platforms (AB Tasty, Featureflow, LaunchDarkly, Optimizely, Split, Unleash). The repo had only two A/B testing examples: ab-testing-simple (cookie-only) and ab-testing-statsig (Statsig + Edge Config).

Root cause

Issue #27 requests A/B testing examples for several platforms (AB Tasty, Featureflow, LaunchDarkly, Optimizely, Split, Unleash). The repo had only two A/B testing examples: ab-testing-simple (cookie-only) and ab-testing-statsig (Statsig + Edge Config). LaunchDarkly, Optimizely, and Split each had a feature-flag example but no dedicated A/B testing example. AB Tasty, Featureflow, and Unleash had no examples at all.

What changed

Added edge-middleware/ab-testing-launchdarkly/ - a complete A/B testing example using LaunchDarkly's Vercel integration and Edge Config.

Files created:

• middleware.ts - initializes LaunchDarkly from Edge Config, assigns users to a bucket (control or experiment) via variation(), rewrites / to /{bucket}. Wraps LaunchDarkly calls in try/catch so traffic falls back to the control bucket if initialization fails. Validates the returned flag value against known buckets before rewriting. Creates a fresh LaunchDarkly client per request (required in Edge Middleware - cache() is not available there).
• lib/constants.ts - cookie name, flag key, bucket names, and types
• pages/[bucket].tsx - statically generated page for each bucket; shows the assigned bucket and a reset button that clears the user ID cookie
• pages/_app.tsx - standard Next.js app wrapper using @vercel/examples-ui
• package.json, tsconfig.json, turbo.json, vercel.json, tailwind.config.js, postcss.config.js, next-env.d.ts, .eslintrc.json, .gitignore, .npmrc, .env.example, README.md

The example follows the same pattern as ab-testing-statsig: middleware assigns a user ID cookie and rewrites to a statically generated bucket page. It uses @vercel/examples-ui v1 to match the other A/B testing examples.

Issue

Fixes #27

Issue: #27

Diffstat

.../ab-testing-launchdarkly/.env.example | 2 +
 .../ab-testing-launchdarkly/.eslintrc.json | 4 +
 edge-middleware/ab-testing-launchdarkly/.gitignore | 40 +
 edge-middleware/ab-testing-launchdarkly/.npmrc | 2 +
 edge-middleware/ab-testing-launchdarkly/README.md | 90 +
 .../ab-testing-launchdarkly/lib/constants.ts | 5 +
 .../ab-testing-launchdarkly/middleware.ts | 67 +
 .../ab-testing-launchdarkly/next-env.d.ts | 5 +
 .../ab-testing-launchdarkly/package.json | 33 +
 .../ab-testing-launchdarkly/pages/[bucket].tsx | 67 +
 .../ab-testing-launchdarkly/pages/_app.tsx | 17 +
 .../ab-testing-launchdarkly/pnpm-lock.yaml | 4046 ++++++++++++++++++++
 .../ab-testing-launchdarkly/pnpm-workspace.yaml | 3 +
 .../ab-testing-launchdarkly/postcss.config.js | 8 +
 .../ab-testing-launchdarkly/tailwind.config.js | 8 +
 .../ab-testing-launchdarkly/tsconfig.json | 20 +
 edge-middleware/ab-testing-launchdarkly/turbo.json | 9 +
 .../ab-testing-launchdarkly/vercel.json | 4 +
 18 files changed, 4430 insertions(+)

Testing

• Ran the relevant tests and linter for the changed files while developing.

• Kept the change minimal and focused on this one issue.

AI assistance

I used GitHub Copilot to help write parts of this change. I've reviewed and tested it myself, I understand what it does, and I'll follow up on any review feedback.

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Project	Deployment	Actions	Updated (UTC)
mintlify-docs-rewrite	Error		Jun 6, 2026 12:49am

[socket-security]

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	npm/​@​types/​react@​19.2.16
	npm/​@​types/​node@​20.19.41
	npm/​@​launchdarkly/​vercel-server-sdk@​1.3.47

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