Feature flag utilities

URL-based feature flag helpers in @genesislcap/foundation-utils let you enable or disable behaviour without a separate build. Flags appear in the query string as feature.<name>.

info

For API signatures, see isFeatureActivated in the API documentation. The Foundation Header Feature Flags control uses these helpers to sync selection with the URL.

Key features

• isFeatureActivated(name) — true when feature.<name> is present in the current URL (any truthy presence of the key).
• getActivatedFeatures() — names of all feature.* flags currently in the URL.
• setActivatedFeatures(names, options?) — rewrites URL feature.* params to match names (each selected flag is written as feature.<name>=true). Reloads by default so boot-time consumers re-evaluate; pass { reload: false } to update via history.replaceState only.

Usage

import {
  getActivatedFeatures,
  isFeatureActivated,
  setActivatedFeatures,
} from '@genesislcap/foundation-utils';

// URL: https://example.com/app?feature.darkMode=true
console.log(isFeatureActivated('darkMode')); // true
console.log(getActivatedFeatures()); // ['darkMode']

// Enable ai + forceHttp (reloads the page by default)
setActivatedFeatures(['ai', 'forceHttp']);

// Update the URL without reloading
setActivatedFeatures(['ai'], { reload: false });

URL format

https://your-app.com/?feature.newDashboard=true&feature.experimentalApi=1

Any truthy presence of feature.<name> activates that flag. Prefer setActivatedFeatures with the default reload when toggling flags that are read at boot time.

Considerations

• Flags are evaluated at runtime from the current URL — useful for testing and gradual rollouts.
• URL flags are visible to users; do not use them for security-sensitive controls.
• Pair with the header Feature Flags selector when you want an in-app UI for toggling the same parameters.