Messagevisor

Featurevisor module

@messagevisor/module-featurevisor connects Messagevisor feature and experiment conditions to an existing Featurevisor SDK instance.

Install

Command
$ npm install --save \
    @messagevisor/sdk \
    @messagevisor/module-featurevisor \
    @featurevisor/sdk

SDK setup

Create your Featurevisor instance first, then pass it to the Messagevisor module:

JavaScript
import { createInstance } from "@featurevisor/sdk";
import { createMessagevisor } from "@messagevisor/sdk";
import { createFeaturevisorModule } from "@messagevisor/module-featurevisor";
const f = createInstance({
  datafile: featurevisorDatafile,
});
const m = createMessagevisor({
  datafile: messagevisorDatafile,
  modules: [
    createFeaturevisorModule({
      instance: f,
      // passContext: true, // `false` by default
    }),
  ],
});

The module registers resolvers on the Messagevisor SDK instance:

  • feature conditions call f.isEnabled(featureKey)
  • experiment conditions call f.getVariation(experimentKey)

By default, Messagevisor does not pass its own evaluation context to Featurevisor. Enable passContext when you want Messagevisor's SDK-level and per-call context to be forwarded to Featurevisor evaluations.

Feature conditions

Use feature conditions when a translation override should follow a Featurevisor flag:

messages/checkout/title.yml
translations:
  en: Checkout
overrides:
  - key: new-checkout
    conditions:
      feature: new-checkout
      operator: isEnabled
    translations:
      en: Faster checkout

You can also match when the flag is disabled:

overrides:
  - key: classic-checkout
    conditions:
      feature: new-checkout
      operator: isDisabled
    translations:
      en: Classic checkout

Experiment conditions

Use experiment conditions when copy should follow the active Featurevisor variation:

messages/checkout/cta.yml
translations:
  en: Continue
overrides:
  - key: bold-copy
    conditions:
      experiment: checkout-copy
      operator: hasVariation
      value: bold
    translations:
      en: Try the faster checkout

The experiment key maps to the Featurevisor feature key passed to getVariation. If Featurevisor returns null, the condition does not match.

Context

By default, the module relies on context already configured on the Featurevisor instance. Messagevisor context is not forwarded:

JavaScript
const m = createMessagevisor({
  datafile: messagevisorDatafile,
  context: {
    platform: "web",
  },
  modules: [createFeaturevisorModule({ instance: f })],
});

Set passContext: true when Featurevisor should receive Messagevisor's combined SDK-level and per-call context:

JavaScript
const m = createMessagevisor({
  datafile: messagevisorDatafile,
  context: {
    platform: "web",
  },
  modules: [createFeaturevisorModule({ instance: f, passContext: true })],
});
m.translate("checkout.title", {}, {
  context: {
    userId: "user-123",
  },
});

With passContext: true, Featurevisor receives { platform: "web", userId: "user-123" } for the flag or variation evaluation.

Project setup

Register the module wherever Messagevisor runtime evaluation happens. In application code, add it to the SDK instance as shown above.

If CLI workflows such as evaluate, examples, tests, or catalog output need Featurevisor-backed conditions, register the module in messagevisor.config.js and provide a Featurevisor instance that can be created in that environment:

messagevisor.config.js
const { createInstance } = require("@featurevisor/sdk");
const { createFeaturevisorModule } = require("@messagevisor/module-featurevisor");
const f = createInstance({
  datafile: require("./featurevisor-datafile.json"),
});
module.exports = {
  modules: [createFeaturevisorModule({ instance: f })],
};

Edge cases and behavior notes

Keys map directly

Messagevisor passes the authored feature or experiment key directly to Featurevisor.

Module order usually does not matter

This module registers condition resolvers during setup. It does not format or transform message output, so it can usually be placed before or after formatting modules.

No resolver means no match

Without this module, or another resolver integration, Messagevisor feature and experiment conditions evaluate as non-matches.