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Using the JavaScript SDK

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Getting a Feature Flag​

To retrieve a Feature Flag, use the getFlag function:

AppFlags.getFlag("flag_key", flag => {
    const value = flag.value;
});

Subscribing to a Feature Flag​

To subscribe to a Feature Flag and get realtime updates, use the onFlagChanged function:

AppFlags.onFlagChanged("flag_key", flag => {
    const value = flag.value;
});

When the feature flag is updated, onFlagChanged will be invoked immediately.

Note that onFlagChanged resolves with the current Feature Flag, so there is no need to call getFlag as well.

Flag Properties​

The Flag object contains the following properties:

  • key: the key identifier for the Feature Flag
  • value: the value of the active Variation, either a boolean, number, or string

Example Repository​

For a full example of using AppFlags in a JavaScript application, see https://github.com/AppFlags/example-javascript.