---
title: Example usage of the JavaScript (Node) SDK prior to v6
slug: feature-experimentation/docs/example-usage-javascript-node-prior-to-v6
docTags: 
createdAt: 2026-08-05T20:39:52.000Z
---

After installing the JavaScript (Node) SDK, import the Optimizely library, get your project's datafile, and create a client. Use the client to evaluate flag rules like A/B tests and flag deliveries.

This example walks through the following three key steps:

1. Evaluate a flag with the key `product_sort` using the `decide` method. This also sends a decision event to Optimizely to record that the user was exposed to the experiment.
2. Run code based on the flag result. The SDK evaluates your flag rules and determines which variation the user is in. You can either:
   - Check the flag's enabled state and read a configuration variable (`sort_method`) to determine which experience the user gets.
   - Check the flag variation directly and run the corresponding control or treatment code.
3. Track a conversion event called `purchased` to measure the experiment's impact. The `trackEvent` method ties the purchase back to the A/B test and sends it to Optimizely so it displays on your [Experiment Results page](docId:_K6n7h_MZ8b0xn6yWPrrq).

```javascript
const { createInstance } = require('@optimizely/optimizely-sdk');

const optimizely = createInstance({
  sdkKey: '<YOUR_SDK_KEY>' // Provide the sdkKey of your desired environment here
});

if (optimizely) {
  optimizely.onReady().then(({ success, reason }) => {
    if (!success) {
      throw new Error(reason);
    }

    const attributes = { logged_in: true };
    const user = optimizely.createUserContext('user123', attributes);

    if (!user) {
      throw new Error('failed to create user context');
    }

    const decision = user.decide('product_sort');
    const variationKey = decision['variationKey'];

    if (variationKey === null) {
      console.log(' decision error: ', decision['reasons']);
    }

    const enabled = decision['enabled'];

    if (enabled) {
      const sortMethod = decision.variables['sort_method'];
      // execute code for sort method value
    }

    if (variationKey === 'control') {
      // Execute code for control variation
    } else if (variationKey === 'treatment') {
      // Execute code for treatment variation
    }

    // Track an event
    user.trackEvent('purchased');
  }).catch((err) => {
    // handle error
  });
} else {
  // there was an error creating the instance, handle error
};
```