JavaScript SDK

For browser based web applications.
Installation
npm add @featureboard/js-sdk
# Or
yarn add @featureboard/js-sdk
# Or
pnpm add @featureboard/js-sdk
Getting started
const { client, close } = await FeatureBoardService.init('env-api-key', ['audiences', 'of', 'user'], {
    /* options */
})
​
const featureValue = client.getFeatureValue('my-feature-key', fallbackValue)
​
const unsubscribe = subscribeToFeatureValue('my-feature-key', fallbackValue, (onValue) => {
    // Will be called with the initial value and subsiquent updates
})
​
// Remove subscription
unsubscribe()
NOTE: You must specify a fallback value, this value is used when the feature is unavailable in the current environment.
Options
The optional third argument to init
initialValues
Provides the SDK with a set of initial flag values, if provided the subscription and update of the feature state will happen in the background. Allowing you to immediately use the SDK
updateStrategy
Configure how the FeatureBoard SDK gets updated values, default 'live'
live
Connects to the FeatureBoard service using web sockets, giving near realtime updates
polling
Polls for updates using http. Default polling interval 30 seconds.
manual
If you would like to control when feature state is updated, or not have updates just choose 'manual'
const { client, updateFeatures } = await FeatureBoardService.init('env-api-key', ['audiences', 'of', 'user'], {
    updateStrategy: 'manual',
    /* options */
})
​
// Triggers an update of the feature state
updateFeatures()
TypeScript
To get type safety on your features you can use Declaration Merging to define the features
declare module '@featureboard/js-sdk' {
    interface Features {
        'my-feature-key': string
    }
}

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