feature-toggles

    1.4.0 • Public • Published

    feature-toggles

    Simple implementation of feature toggles for JavaScript (also called feature flipping).

    Features

    This module encapsulates all calls to check if a certain feature (toggle) is enabled. Furthermore it provides the possibility to have computed feature toggle values in form of functions.

    Simple toggle values

    Example for using plain values:

    // define toggles
    var toggles = {foo: true, bar: false};
     
    // load them into the module
    var featureToggles = require('feature-toggles');
    featureToggles.load(toggles);
     
    // check if a feature is enabled
    if (featureToggles.isFeatureEnabled('foo')) {
        // do something
    }

    Computed toggle values

    For computed values provide a function for the value of a feature toggle. Whenever checking if the feature is enabled the provided function will be invoked. All arguments passed to the isFeatureEnabled() call except the first one are passed on to the function.

    Example:

    // define a computed toggle
    var toggles = {
        foo: function(a, b) {
            return (== 'a' && b == 'b');
         }
    }
     
    // load them into the module
    var featureToggles = require('feature-toggles');
    featureToggles.load(toggles);
     
    // check if a feature is enabled and provide additional arguments
    if (featureToggles.isFeatureEnabled('foo', 'a', 'b') {
        // do something
    }

    If the function throws an exception the isFeatureEnabled() call will return false to prevent runtime crashes.

    Advanced examples (pseudo code)

    Enabling a toggle based on an url parameter within an express app:

    var toggles = {
        foo: function(request) {
            return request.param('enableFoo');
        }
    }
     
    var featureToggles = require('feature-toggles');
    featureToggles.load(toggles);
     
    app.get('/', function(request, response) {
        if (featureToggles.isFeatureEnabled('foo', request)) {
            // do something
        }
    });

    Enabling a toggle based on a certain date:

    var toggles = {
        foo: function() {
            var date = new Date();
            return date.getDate() > 15;
        }
    }
     
    var featureToggles = require('feature-toggles');
    featureToggles.load(toggles);
     
    if (featureToggles.isFeatureEnabled('foo')) {
        // do something
    }

    Express integration

    Use the middleware to easily toggle features per request. This way a special version of isFeatureEnabled() is exposed to all views (res.locals). Computed toggles will automatically receive the current request and response as arguments.

    var toggles = {
        foo: function(request, response) {
            return request.param('enableFoo');
        }
    }
    var application = express();
     
    application.use(featureToggles.middleware);
    - if (isFeatureEnabled('foo'))
        Foo is enabled

    Alternative modules

    Keywords

    none

    Install

    npm i feature-toggles

    DownloadsWeekly Downloads

    2,420

    Version

    1.4.0

    License

    MIT

    Last publish

    Collaborators

    • alexlawrence