Key-Function store for registering and checking features and variants.
A simple singleton key-function store for registering feature toggles and variant values.
You use npm right?
npm install flip-js
Flip is a singleton, so everytime you
require('flip') it will return the same instance. It's inspired by routes in express and template helpers in handlebars if you're familiar with either of those.
You'll want to
register features somewhere in your server setup.
var flip = require'flip';flipregister'my-feature'return subjectisAdmin;;
Then somewhere in your route or request handler you can
if the feature should be enabled.
var flip = require'flip';var templateContext ='my-feature-enabled': flipcheck'my-feature' requser;;
You can also run checks asynchronously by providing a callback to the
var flip = require'flip';flipcheck'my-feature' requservar templateContext ='my-feature-enabled': myFeature;;;
Flip comes with a few baked
Most times you just have a list of keys (users for example) that should have the feature enabled. In this case you can provide a list of the blessed users and be on your way.
// Register a feature and provide a list of blessed usersflipregister'my-feature' flipbundledblessedList'drk' 'astro';// Then provide the user in the check to see if the feature should be enabledflipcheck'my-feature' 'drk'; // trueflipcheck'my-feature' 'bogus'; // false
Another common use case is a/b testing or providing a variant per session. Here you can provide a hash of variants where the values are list of keys (users for example) for each variant.
var variants =awesome: 'astro'favorite: 'drk';flipregister'my-variant' flipbundledvariantvariants;// Check for variant for a given userflipcheck'my-variant' 'astro'; // 'awesome'flipcheck'my-variant' 'drk'; // 'favorite'flipcheck'my-variant' 'bogus'; // false (no variant has been assigned!)
In the last example —
'bogus' — no variant has been assigned. You can handle the
logic here for assigning a variant for
'bogus' and then register the variant again. In this case the variants are stored in memory which isn't extremely useful, but no reason you couldn't use another store like redis.