featureguards-node

Javascript SDK for FeatureGuards (Node + Browser)

The official FeatureGuards NodeJS Javascript client library.

NodeJS

The FeatureGuards Node library provides convenient access to the FeatureGuards API from applications written in server-side JavaScript.

For using FeatureGuards in the browser, use [featureguards-web][featureguards-web].

Requirements

Node 8, 10 or higher.

Installation

Install the package with:

npm install featureguards-node --save
# or
yarn add featureguards-node

Usage

The package needs to be configured with your API key, which is available in the Featureguards Dashboard. Require it with the key's value:

Usage with modules and async/await:

import featureguards from 'featureguards-node';
const featureGuards = await featureguards({
  apiKey: 'MY API KEY'
})(async () => {
  const isOn = await featureguards.isOn('MY_FEATURE_GUARD');
  console.log(isOn);
})();

Usage with Promises

Every method returns a chainable promise which can be used instead of a regular callback:

// Check a feature flag is on or not:
featureGuards.isOn('MY_FEATURE')
  .then((isOn) => {
    // Deal with whether the feature is on or off.
    })
    .catch((err) => {
    // Deal with an error
    });
  });

Usage with TypeScript

Import featureguards as a default import passing it the API key and use it.

import featureguards from 'featureguards-node';

const featureGuards = await featureguards({
  apiKey: 'MY API KEY'
});
const isOn = await featureguards.isOn('MY_FEATURE_GUARD');
console.log(isOn);

You can find a full TS server example in featureguards-js.

Configuring default values

FeatureGuards does no I/O for isOn because it keeps a fresh copy for all features defined in the dashboard. In the event the initial fetch doesn't succeed, the library can use default values passed by the caller. This is useful for features that have graduated and no longer need to be guarded by a feature flag, but may want to keep an emergency toggle to turn off the feature in case something bad happens, hence not removing them completely from FeatureGuards. This concept is referred to as 'kill switch'. Here is an example of how to do so.

Javascript

import featureguards from 'featureguards-web';
const featureGuards = await featureguards({
  apiKey: 'MY API KEY',
  defaults: {
    MY_FEATURE_GUARD: true
  }
})(async () => {
  const isOn = await featureguards.isOn('MY_FEATURE_GUARD');
  console.log(isOn);
})();

Typescript

import featureguards from 'featureguards-web';
const featureGuards = await featureguards({
  apiKey: 'MY API KEY',
  defaults: {
    MY_FEATURE_GUARD: true
  }
})(async () => {
  const isOn = await featureguards.isOn('MY_FEATURE_GUARD');
  console.log(isOn);
})();

Development

Run all tests:

$ yarn install
$ yarn test

If you do not have yarn installed, you can get it with npm install --global yarn.

Run prettier:

Add an editor integration or:

$ yarn fix