featureling 
Feature handling package to assist in versioning an api. The package provides the necessary hooks to make a feature list avaliable. It was created to provide the concept of a feature to use for versioning your code. It is utilizing CLS to make the feature list available for an application.
Usage
There are two main methods.
create - Middleware to look at the Accept-Version header and determine available features. This list of feature is place in CLS for use later.
has - Checks if a version is available. This can be used to determine if custom code or legacy behavior needs to be applied.
Examples
create usage
Use the feature list in your application package.json and the Accept-Version header to determine features available.
app.use(require('featureling').create(require('./package.json').features));
Feature List
Your feature list will look something like the following:
"features":{
"1.x":[ "versions","health","lists"],
"0.x":[ "health"]
}
has usage
You can then lookup to see if the feature is available.
featureling.has("versions")