@justintout/feature-flags

feature-flags

Simple feature flags

@justintout/feature-flags exports a singleton Features that allows you to manage boolean feature flags.

Installation

npm i @justintout/feature-flags

Usage

import { Features } from '@justintout/feature-flags';

Features.add(
    {name: 'debugMode', enabled: false, onToggled: (_) => console.info('debug mode has been enabled!')}
);

Features.listen();

if (Features.enabled('debugMode')) {
    console.info('debug mode is enabled!');
}

Features.toggle('debugMode');

window.emit

Features

Features are objects with a name that track a boolean enabled value. Features can carry an optional description.

Features can be "dynamic" by providing a ToggleFunction in onToggled. The onToggled function will run whenever the feature is toggled. The onToggled function will not run when the feature is initially added.

Add features

Features are added with Features.add(). Adding a feature with an existing name will overwrite the feature.

> Features.add({name: 'debugMode', enabled: false});

Enabled feature

Test if a feature is enabled with Features.enabled(). This returns the current state of the feature. This returns false if the feature doesn't exist.

> Features.enabled('debugMode');
false

Toggle features

Features are toggled with Features.toggle(). This returns the new state of the feature.

Features that don't exist can not be toggled. Features.toggle() will silently return false.

> Features.toggle('debugMode');
true

Features status

Get the state of all features with Features.status(). This returns an object with added features as keys and their current state as values.

> Features.status();
{ debugMode: true }

Toggle features across the global scope

It may be helpful to be able to toggle features outside of the package itself. Calling Features.listen() will add a function toggleFeature() to global scope. This would allow a debug page to change feature settings on the fly.

Passing false will remote toggleFeatures().

> Features.listen();
undefined
> global.toggleFeature('debugMode');
true

Contributing

Pull requests are welcome.