AUTO_RESETS.md

Auto Resets

Disclaimer: Typically, this feature is not recommended if you can scope your FeatureToggles instances to shorter lifespans (see: Scoping). If the value of a toggle were to change mid-way through an asynchronous operation within your application, the operation may produce unexpected results. Use with care.

Some dependencies may be more dynamic than others; a simple example is the Hobknob client.

Note: Even with the hobknob client running server-side, typically, you would want to wait until you have finished processing your request before updating the toggle. By scoping the toggles to the request, you can avoid needing to use the auto reset feature.

To keep your application lean and fast, the smart-feature-toggle client uses a synchronous api and the value of each toggle is calculated only once per FeatureToggles instance.

If your dependent service may update, we provide a resetOn callback property. This callback will recieve a reset method that you may use at any time to force the calculated value to be forgotten so that it may be re-calculated the next time it is queried.

const features = [{
    name: 'my-feature-123',
    ...,
    resetOn: (reset) => {
        hobknob.on('updated-cache', (changed) => {
            if(changed.find(toggle => toggle.name === 'my-feature-123')) {
                reset();
            }
        })
    }
}]

Live updates

Another use case would be to implement live feature toggling in the browser. This would allow you to produce this sort of effect:

MPJ toggles what the default sorting should be from Time sorting to Natural sorting and the react application changes without requiring the user to refresh: (YouTube) Incremental rollout and targeting individual users - #3 LaunchDarkly Feature Flags by Fun Fun Function @5m27s