A lightweight A/B Testing and Feature Flag React library focused on performance ⚡️

Tesfy provides a simple but complete solution to develop A/B Tests and Feature Flags on both server and client side without relying in any storage layer. The main features of this library are:

• Lightweight and focused on performance
• Experiments
• Feature Flags
• Audience definition using jsonLogic
• Traffic Allocation
• Sticky Bucketing

Usage

Installation

npm install react-tesfy --save

Initialization

Render the provider with a datafile. A datafile is a json that defines the experiments and features avaliable. Ideally this file should be hosted somewhere outside your application (for example in S3), so it could be fetched during boostrap or every certain time. This will allow you to make changes to the file without deploying the application.

import { TesfyProvider } from 'react-tesfy';

const datafile = {
  experiments: {
    'experiment-1': {
      id: 'experiment-1',
      percentage: 90,
      variations: [{
        id: '0',
        percentage: 50
      }, {
        id: '1',
        percentage: 50
      }]
    },
    'experiment-2': {
      id: 'experiment-2',
      percentage: 100,
      variations: [{
        id: '0',
        percentage: 100
      }],
      audience: {
        '==' : [{ var : 'countryCode' }, 'us']
      }
    }
  },
  features: {
    'feature-1': {
      id: 'feature-1',
      percentage: 50
    }
  }
};
const userId = '676380e0-7793-44d6-9189-eb5868e17a86';

const App = () => (
  <TesfyProvider datafile={datafile} userId={userId}>
    {children}
  </TesfyProvider>
);

Experiments

Check which variation of an experiment is assigned to a user.

import { useExperiment, Experiment, Variation } from 'react-tesfy';

const Hook = () => {
  const variationId = useExperiment({ id: 'experiment-1' }); // '1'
};

const Simple = () => (
  <Experiment id="experiment-1">
    <Variation>
      Not rendered
    </Variation>
    <Variation id="0">
      Not rendered
    </Variation>
    <Variation id="1">
      Rendered
    </Variation>
  </Experiment>
);

Feature Flags

Check if a feature is enabled for a user.

import { Feature } from 'react-tesfy';

const Hook = () => {
  const isEnabled = useFeature({ id: 'feature-1' }); // true
};

const Simple = () => (
  <Feature id="feature-1">
    {isEnabled => isEnabled ? 'enabled' : 'disabled'}
  </Feature>
);

Audiences

Use attributes to target an specific audience.

import { useExperiment, Experiment, Variation } from 'react-tesfy';

const Hook = () => {
  const id = 'experiment-2';
  const variationId1 = useExperiment({ id, attributes: { countryCode: 've' } }); // null
  const variationId2 = useExperiment({ id, attributes: { countryCode: 'us' } }); // '0'
};

const Simple = () => (
  <Fragment>
    <Experiment id="experiment-2" attributes={{ countryCode: 've' }}>
      <Variation>
        Rendered
      </Variation>
      <Variation id="0">
        Not rendered
      </Variation>
    </Experiment>
    
    <Experiment id="experiment-2" attributes={{ countryCode: 'us' }}>
      <Variation>
        Not endered
      </Variation>
      <Variation id="0">
        Rendered
      </Variation>
    </Experiment>
  </Fragment>
);

Feedback

Pull requests, feature ideas and bug reports are very welcome. We highly appreciate any feedback.