Examples

Release a checkout rewrite

const flags = featureFlags({
  name: "main",
  flags: {
    checkoutV2: flag.boolean({
      default: false,
      environments: {
        preview: true,
      },
      rules: [
        flag.tenants(["tenant_acme"]).value(true),
      ],
    }),
  },
})

app.get("/checkout", async (request) => {
  const tenantId = request.headers.get("x-tenant-id") ?? "public"
  const enabled = await flags.enabled("checkoutV2", {
    tenantId,
    environment: request.env.NODE_ENV === "production" ? "prod" : "preview",
  })

  return Response.json({
    checkoutVersion: enabled ? "v2" : "v1",
  })
})

Roll out a new pricing page

const flags = featureFlags({
  name: "main",
  flags: {
    pricingPageVariant: flag.variant({
      default: "control",
      variants: ["control", "short-copy", "new-layout"],
      rules: [
        flag.percentage(20, { stickiness: "tenantId" }).value("new-layout"),
      ],
    }),
  },
})

Raise a runtime limit

const flags = featureFlags({
  name: "main",
  flags: {
    maxUploadMb: flag.number({
      default: 25,
      environments: {
        prod: 50,
      },
    }),
  },
})

const maxUploadMb = await flags.value<number>("maxUploadMb", {
  environment: "prod",
  default: 25,
})