Neff is simple express middleware for handling feature flags.
Usage
The standard way to use neff on the client & the server side is to check for enabled features using the isEnabled() API.
var users = 500;var moreUsers = neff;if moreUsers users++;Argument-Based Config
To get started with neff you'll want to make sure you call neff, passing it an object with feature names and either true or false values.
var neff = require("neff")({
"feature1": true,
"feature2": false
});
app.use(neff);
NConf-Based Config
If you'd like to utilize NConf for this, you can reference an NConf JSON file and my config looks like this:
"features": Then pass the config object for the features to neff:
var neff = require("neff")(nconf.get('features'));
app.use(neff);
Accessing in templates
The first thing it allows you to do is access feature flags directly in your template such as (dust syntax):
{?feature-feature1}
MY HIDDDEN CODE
{/feature-feature1}
Express Router Limiter
This route is only available when the feature flag is enabled. Otherwise the user would see a server error page.
var neff = ;app;Client Side Usage
It also provides a string of class names you can insert into your <body> (dust syntax):
The output prepends feature- to the classname, so you might see something like <body class="feature-feature1"> with the config above. Only enabled features show up in the string.
Make sure your features are declared on your DOM like so:
<body class="feature-feature1 feature-feature2">
Once you've done that you can take advantage of the flags in 2 ways.
CSS
/* Create a block that's hidden by default */ /* Display that block when your flag is present */JavaScript
;Thanks
Inspired heavily by https://npmjs.org/package/feature-gateway.