featuring

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featuring is a simple lightweight immutable feature toggle JavaScript library.

• Install
• API
• Bugs
• Contributors
• License

Install

Install using the package manager for your desired environment(s):

$ npm install --save featuring
# OR:
$ bower install --save featuring

While equals should be compatible with all versions of Node.js, it is only tested against version 4 and above.

If you want to simply download the file to be used in the browser you can find them below:

• Development Version (15kb - Source Map)
• Production Version (1.2kb - Source Map)

API

All feature names that are passed to the API are case sensitive.

Featuring([features])

Encapsulates the named active features provided, allowing them to be queried at any time while preventing them from being modified.

var Featuring = require('featuring');
var features = new Featuring([ 'FOO', 'BAR' ]);
// OR:
var featuring = require('featuring');
var features = featuring([ 'FOO', 'BAR' ]);
 
features.active('FOO');
//=> true
features.active([ 'FOO', 'BUZZ' ]);
//=> false
features.anyActive([ 'FOO', 'BAR' ]);
//=> true
 
features.get();
//=> [ "FOO", "BAR" ]
 
features.verify('FOO');
// ...
features.verify([ 'FOO', 'BUZZ' ]);
//=> Error("BUZZ" feature is not active)
features.verifyAny([ 'FOO', 'BAR' ]);
// ...
 
features.when('FOO', function() {
 // ...
});
features.when([ 'FOO', 'BUZZ' ], function() {
 // Never called
});
features.whenAny([ 'FOO', 'BAR' ], function() {
 // ...
});

Featuring#active([names])

Returns whether all of the named features are active.

var features = require('featuring')([ 'FOO', 'BAR' ]);
 
features.active('FOO');
//=> true
features.active('BUZZ');
//=> false
features.active([ 'FOO', 'BAR' ]);
//=> true
features.active([ 'FOO', 'BUZZ' ]);
//=> false
features.active([ 'foo', 'bar' ]);
//=> false
 
features.active(null);
//=> true
features.active([]);
//=> true

Featuring#anyActive([names])

Alias: Featuring#active.any

Returns whether any of the named features are active.

var features = require('featuring')([ 'FOO', 'BAR' ]);
 
features.anyActive('FOO');
//=> true
features.anyActive('BUZZ');
//=> false
features.anyActive([ 'FOO', 'BAR' ]);
//=> true
features.anyActive([ 'FOO', 'BUZZ' ]);
//=> true
features.anyActive([ 'foo', 'bar' ]);
//=> false
 
features.anyActive(null);
//=> false
features.anyActive([]);
//=> false

Featuring#get()

Returns the names of all of the active features.

var featuring = require('featuring');
 
featuring([]).get();
//=> []
featuring('FOO').get();
//=> [ "FOO" ]
featuring([ 'FOO', 'BAR' ]).get();
//=> [ "FOO", "BAR" ]

Featuring#verify([names])

Verifies that all of the named features are active and throws an error if they are not.

This method is useful for fail-fast situations where it's best if the code simply breaks when the named features are not active.

var features = require('featuring')([ 'FOO', 'BAR' ]);
 
features.verify('FOO');
// ...
features.verify('BUZZ');
//=> Error("BUZZ" feature is not active)
features.verify([ 'FOO', 'BAR' ]);
//=> ...
features.verify([ 'FOO', 'BUZZ' ]);
//=> Error("BUZZ" feature is not active)
features.verify([ 'foo', 'bar' ]);
//=> Error("foo" feature is not active)
 
features.verify(null);
// ...
features.verify([]);
// ...

Featuring#verifyAny([names])

Alias: Featuring#verify.any

Verifies that any of the named features are active and throws an error if this is not the case.

This method is useful for fail-fast situations where it's best if the code simply breaks when none of the named features are active.

var features = require('featuring')([ 'FOO', 'BAR' ]);
 
features.verifyAny('FOO');
// ...
features.verifyAny('BUZZ');
//=> Error(All named features are not active)
features.verifyAny([ 'FOO', 'BAR' ]);
//=> ...
features.verifyAny([ 'FOO', 'BUZZ' ]);
// ...
features.verifyAny([ 'foo', 'bar' ]);
//=> Error(All named features are not active)
 
features.verifyAny(null);
//=> Error(All named features are not active)
features.verifyAny([]);
//=> Error(All named features are not active)

Featuring#when([names, ]func)

Invokes the specified function only when all of the named features are active.

This method is often preferred over using Featuring#active within an if expression when wrapping large code as it helps to prevent potential scoping issues (e.g. from variable hoisting) and can even be simpler to replace with IIFEs, when taking that route.

var features = require('featuring')([ 'FOO', 'BAR' ]);
 
features.when('FOO', function() {
  // ...
});
features.when('BUZZ', function() {
  // Never called
});
features.when([ 'FOO', 'BAR' ], function() {
  // ...
});
features.when([ 'FOO', 'BUZZ' ], function() {
  // Never called
});
features.when([ 'foo', 'bar' ], function() {
  // Never called
});
 
features.when(null, function() {
  // ...
});
features.when([], function() {
  // ...
});

Featuring#whenAny([names, ]func)

Alias: Featuring#when.any

Invokes the specified function only when any of the named features are active.

This method is often preferred over using Featuring#anyActive within an if expression when wrapping large code as it helps to prevent potential scoping issues (e.g. from variable hoisting) and can even be simpler to replace with IIFEs, when taking that route.

var features = require('featuring')([ 'FOO', 'BAR' ]);
 
features.whenAny('FOO', function() {
  // ...
});
features.whenAny('BUZZ', function() {
  // Never called
});
features.whenAny([ 'FOO', 'BAR' ], function() {
  // ...
});
features.whenAny([ 'FOO', 'BUZZ' ], function() {
  // ...
});
features.whenAny([ 'foo', 'bar' ], function() {
  // Never called
});
 
features.whenAny(null, function() {
  // Never called
});
features.whenAny([], function() {
  // Never called
});

Bugs

If you have any problems with featuring or would like to see changes currently in development you can do so here.

Contributors

If you want to contribute, you're a legend! Information on how you can do so can be found in CONTRIBUTING.md. We want your suggestions and pull requests!

A list of featuring contributors can be found in AUTHORS.md.

License

Copyright © 2018 Alasdair Mercer

See LICENSE.md for more information on our MIT license.