Feature Toggle Client

Usage

First, install client

``
npm i -S feature-toggle-client
`

Initialize user or application with a payload and LauchDarkly key.
You also can intialize the Launch Darkly API with an Authorization Token, Project Key and Environment Key.

`typescript
import { FeatureToggleClientService } from 'feature-toggle-client'

const init = () => {
// Initialize user instance
FeatureToggleClientService
.initializeUser({
fullName: 'My incredible name',
email: 'user@email.com', // LauchDarkly user key
}, 'YOUR-LAUNCH-DARKLY-KEY')

// Initialize user application
FeatureToggleClientService
.initializeApplication({
shortName: 'applicationShortName', // LauchDarkly user key
name: 'Application name',
}, 'YOUR-LAUNCH-DARKLY-KEY')

// Initialize api service
FeatureToggleClientService
.initializeApiService({
projectKey: 'project key', // LaunchDarkly project key, (found in: AccountSettings-Projects)
environmentKey: 'environment key', // LaunchDarkly environment key (found in: AccountSettings-Projects)
authorizationToken: 'YOUR-LAUNCH-DARKLY-API-AUTHORIZATION-TOKEN'
});
}
`

While checking for feature value, we recommend decouple a toggling decision point from the logic. (ref). So, we create a class that directly call our client and expose a method like so:

`typescript
const myFeatureFlagKey = 'feature-flag-key';
export class MyFeaturesDecisions {
/**
* Checking for application
**/
public static someFeatureApplicationEnabled(): Promise {
return FeatureToggleClientService
.getInstance()
.isApplicationFeatureEnabled(myFeatureFlagKey)
}

/**
* Checking for user
**/
public static someFeatureUserEnabled(): Promise {
return FeatureToggleClientService
.getInstance()
.isUserFeatureEnabled(myFeatureFlagKey)
}

/**
* Checking for user or application
**/
public static someFeatureEnabled(): Promise {
return FeatureToggleClientService
.getInstance()
.isFeatureEnabled(myFeatureFlagKey)
}
}
`

So, in your controller, we recommend use of an interface IToggleable that implements checkFeatures method. This make class more clearly about it implementation.

`typescript
import { IToggleable } from 'feature-toggle-client'
import { MyFeaturesDecisions } from './MyFeaturesDecisions'

class Foo implements IToggleable {
/**
* Check for features
**/
public async checkFeatures(): Promise {
//Checking for user
this.isUserFeatureEnabled = await MyFeaturesDecisions.someFeatureUserEnabled()

//Checking for application
this.isApplicationFeatureEnabled = await MyFeaturesDecisions.someFeatureApplicationEnabled()
}
}
`

You can add a user to a feature toggle like the code:

`typescript
const myFeatureFlagKey = 'feature-flag-key';
export class MyFeaturesDecisions {
/**
* Adding user to a feature toggle
**/
public static addUserToSomeFeature(): Promise { // true if user was added successfully
return FeatureToggleClientService
.getInstance()
.addUserToFeatureToggle({ email: 'user@mail.com' }, myFeatureFlagKey)
}

/**
* Adding users to a feature toggle
**/
public static addUserToSomeFeature(): Promise { // true if user was added successfully
return FeatureToggleClientService
.getInstance()
.addUserToFeatureToggle(
[{ email: 'user1@mail.com' }, { email: 'user2@mail.com' }],
myFeatureFlagKey)
}
}
`

Running tests

Create file secret.ts following this pattern

`typescript
export const secrectKey = 'YOUR-LAUNCH-DARKLY-KEY';
export const apiAuthorizationToken = 'YOUR-LAUNCH-DARKLY-API-AUTHORIZATION-TOKEN'; //found in: AccountSettings-Authorization
``

That's all!