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Using the Node SDK

  1. Install the Fana Node SDK in your project by running npm i fana-node-sdk
  2. Import the FanaConfig file into whichever files you will be evaluating flags in

const { FanaConfig } = require('fana-node-sdk');

  1. Use the FanaConfig class constructor to instantiate a config object. This constructor takes three arguments:
  • (string) Node SDK key (from your dashboard's settings page)
  • (string) The address of your Flag Bearer
  • (number, optional) Desired Reinitialization Interval
    • You can leave this blank if you do not wish for the SDK to reinitialize. You can find more information about this in the Node SDK Reference
// the sdk key is hard-coded here, but you should have it as an environment variable for security purposes
const config = new FanaConfig('node_key', 'http://localhost:3001', 3600000)
                                ^Node SDK Key  ^Flag Bearer Address   ^Reinitialization Interval
  1. Next, instantiate a FanaClient instance by calling config.connect(). Note that this is an asynchronous action, so you will need to use async/await or promises to perform this step:
// with async/await
let client;

const initializeFanaSDK = async () => {
  client = await config.connect();
};

initializeFanaSDK();

// with promises
let client;

config.connect().then((c) => {
  client = c;
});

Now you can use the FanaClient.prototype.evaluateFlag() method. It takes three arguments:

  • (string) The flag key that you wish to evaluate
  • (object) The user context object
  • (boolean) An optional argument for a default value
app.get("/", (req, res) => {
  // note that the context object is hard-coded here.
  // you will most likely be generating this dynamically
  const userContext = { userId: "jjuy", beta: true };

  if (client.evaluateFlag("beta_processor", userContext, true)) {
    // execute beta processing
  } else {
    // execute regular processing
  }
});