creature-features
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Feature flags for node.js
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# Creature Features
[](https://badge.fury.io/js/creature-features) [](https://travis-ci.org/Kevnz/creature-features) [](https://coveralls.io/github/Kevnz/creature-features?branch=master)
## Dead simple feature flags
Creature-Features allows feature flags based on json configuration files and supports true/false, custom rules, and weighted checks.
### Install
```bash
npm install creature-features --save
```
### Configure
#### directory and files
```
- features
-- default.json (default settings)
-- development.json (settings for development environment)
-- development.{named}.json (settings for individual development environment)
-- test.json (settings for test)
-- production.json (settigns for production)
-- {any other environment}.json
```
#### Example File
```json
{
"FeatureOne": true,
"FeatureTwo": true,
"FeatureThree": false
}
```
### Usage
```javascript
const features = require('creature-features')();
// Default behavior
if (features.FeatureOne) {
// do something new
} else {
// do the old thing
}
```
#### Rules Based
```json
{
"FeatureOne": true,
"FeatureTwo": true,
"RuleForEmailFeature": {
"parameters": "email",
"check": "email.indexOf('test') > -1"
},
"RuleForEmailAndRoleFeature": {
"parameters": "email,role",
"check": "email.indexOf('test') > -1 && role ==='admin'"
}
}
```
```javascript
const features = require('creature-features')();
// Default behavior
if (features.RuleForEmailFeature(user.email)) {
// do something new
} else {
// do the old thing
}
if (features.RuleForEmailAndRoleFeature({ email: user.email, role: user.account.role })) {
// do something new
} else {
// do the old thing
}
```
#### Weight Based
```json
{
"FeatureOne": true,
"FeatureTwo": true,
"PercentBasedFiftyFifty": {
"range": [50, 50]
},
"PercentBasedOneThird": {
"range": [33, 67]
},
}
```
```javascript
const features = require('creature-features')();
// Roughly 50% of the the time this will be true
if (features.PercentBasedFiftyFifty) {
// do something new
}
// Roughly 33% of the the time this will be true
if (features.PercentBasedOneThird) {
// do something new
}
```
### In Webpack
```javascript
const features = require('creature-features')();
const webpack = require('webpack');
const featureFlags = new webpack.DefinePlugin({
FEATURES: features
});
module.exports = {
plugins: [featureFlags],
...
// in a ui file
if (FEATURES.FeatureOne) { }
```
### Why?
* [What are they?](https://martinfowler.com/articles/feature-toggles.html)
* [How are they useful](http://code.flickr.net/2009/12/02/flipping-out/)
* [More info](http://featureflags.io/)
### Advanced Usage
```javascript
const creature = require('creature-features');
const prodFeatures = creature('production');
const locationFeatures = creature({location: './my-location/for-features'});
const bothFeatures = creature({location: './my-location/for-features', env: 'staging'});
```