fflip

fflip

Working on an experimental new design? Starting a closed beta? Rolling out a new feature over the next few weeks? Fa-fa-fa-flip it! fflip gives you complete control over releasing new functionality to your users based on thier user id, join date, membership status, and whatever else you can think of. fflip's goal is to be the most extendable and customizable feature flipping/toggling module out there.

• Create a list of criteria to test your users against
• Describe features as a list of criteria, using easy-to-read json
• Write it all to file, or load it Syncronous/Asyncronous from a database
• *Everything*-Agnostic: Supports any database, user representation or framework you can throw at it

Install with:

npm install fflip

##Getting Started

Below is a simple example of using fflip to deliver a closed beta to a fraction of users:

// Include fflip
var fflip = require('fflip');

fflip.config({
  criteria: ExampleCriteria, // defined below
  features: ExampleFeatures  // defined below
});

// Get a User's Enabled Features
var Features = fflip.featuresForUser(someFreeUser);
if(Features.closedBeta) {
  console.log('Welcome to the Closed Beta!');
}

###Criteria Criteria are the rules that features can test users against. Each rule takes a user and a data argument to test against, and returns true/false if the user matches that criteria. The data argument can be any type, as long as you handle it correctly in the function you describe.

var ExampleCriteria = {    
  isPaidUser: function(user, isPaid) {
    return user.isPaid == isPaid;
  },
  percentageOfUsers: function(user, percent) {
    return (user.id % 100 < percent * 100);
  },
  allowUserIDs: function(user, idArr) {
    for(var id in idArr) {
      if(user.id == idArr[id]) return true;
    }
    return false;
  }
}

###Features Features are sets of criteria to test users against. The value associated with the criteria is passed in as the data argument of the criteria function. A user will have a featured enabled if they match all listed criteria, otherwise the feature is disabled. Features are described as follows:

var ExampleFeatures = {
  paidFeature: {
    isPaidUser: true
  },
  closedBeta: {
    allowUserIDs: [20,30,80,181],
  },
  newFeatureRollout: {
    isPaidUser: false,
    percentageOfUsers: 0.50,
  }
}

##Usage

Object featuresForUser(user)             // Return object of true/false for all features for user
Bool   userHasFeature(user, featureName) // Return true/false for if featureName enabled for user
       config(options)                   // Configure fflip (see below)

Configure fflip using any of the following options:

fflip.config({
  criteria: {}, // Object (see above) or Function (see below)
  features: {}, // Object or Function
  reload: 30,   // Time between refreshing features/criteria, in seconds
});

###Loading Features & Criteria Dynamically fflip also accepts functions for loading criteria and features. If fflip is passed a funciton with no arguments it will call the function and accept the return value. To load asyncronously, pass a function that sends a features/criteria data object to a callback. fflip will recieve the callback and set the data accordingly. Set the reload option to call these functions and refresh the data every X seconds.

// Load Features Syncronously
var getCriteriaSync = function() {
  var collection = db.collection('criteria');
  var criteriaArr = collection.find().toArray();
  /* Proccess criteriaArr -> criteriaObj (format described above) */
  return criteriaObj;
}

// Load Features Asyncronously
var getFeaturesAsync = function(fflip_callback) {
  var collection = db.collection('features');
  collection.find().toArray(function(err, featuresArr) {
    /* Handle err
     * Proccess featuresArr -> featuresObj (format described above) */
    fflip_callback(featuresObj);
  });      
}

fflip.config({
  criteria: getCriteriaSync,
  features: getFeaturesAsync,
  reload: 60 /* Call each function again and update features every 60 secondss */
});

##Special Thanks Switch designed by Luboš Volkov from The Noun Project