Skip to main content

Node SDK Reference

The Node SDK exports two classes:

  • FanaConfig class
  • FanaClient class

FanaConfig​

The FanaConfig class is used to instantiate a config object, which is the first step to setting up with the Node SDK.

FanaConfig Constructor Parameters:​

  • sdkKey: Expects a string representing your Node SDK key. This is provided in the Dashboard's Settings page.
  • bearerAddress: Expects a string representing the address where the Flag Bearer is being hosted.
  • reinitializationInterval: (Optional) Expects an integer representing the number of milliseconds the client should wait between reinitializations. If not provided, there will be no reinitializations. More information about this functionality in the FanaClient.prototype.getFlags() section below.

FanaConfig Instance Methods:​

FanaConfig.prototype.connect()​

  1. Instantiates a FanaClient object
  2. Has the client instance fetch flag data from Flag Bearer
  3. Has the client instance set up SSE connection with Flag Bearer
  4. Returns client instance object

FanaClient​

The FanaClient class generates an object responsible for holding flag data and providing the essential evaluateFlags() method.

FanaClient Constructor Parameters:​

  • config: Expects a FanaConfig object.
  • Note that FanaConfig.prototype.connect() automatically instantiates the client instance for you, so you needn't do this yourself.

FanaClient Instance Methods:​

FanaClient.prototype.evaluateFlag(flagKey, userContext, defaultValue)​

This method takes three arguments:

  • flagKey: Expects a string representing the key of the flag that you wish to evaluate.
  • userContext: Expects an object containing the attributes pertaining to a user or session.
    • { userId: 'jjuy', beta: true, state: 'CA' }
    • This is an example. The attributes you provide will be dependent on your setup.
  • defaultValue: Expects a boolean representing what the evaluation should be in cases where flag data is unavailable or the provided flagKey is invalid. This is optional and is false by default.

This method processes the User Context against the flag targeting settings and returns the evaluation as true or false.

The below methods are called automatically and are only here for reference. You needn't invoke these.

FanaClient.prototype.getFlags()​

This method sends an initialization GET to the Flag Bearer. The Flag Bearer then returns the latest flag ruleset. The client instance then stores it in its flags instance property.

This method is automatically invoked during FanaConfig.prototype.connect().

On Reinitializations/Syncing​

Network failures can potentially cause the SDK to fall out of sync as it may miss an update streamed from the Flag Bearer. To help with this, you can specify a reinitializationInterval when you instantiate your FanaConfig object for the first time. At each interval, the SDK will call getFlags again, refreshing its internal flagset with the latest data.

FanaClient.prototype.setFlag(newFlagKey, newFlagData)​

This method simply updates the client instance's flags instance property with the new data. This occurs when updates are streamed via the SSE connection with the Flag Bearer.

FanaClient.prototype.setStream()​

This method sets up an event source stream with the Flag Bearer. This allows for the client instance to receive real-time updates to flag data.