flgs - The Feature Flag Manager for Node and Javascript

Enables simple feature flagging, feature gating and co. by incorporating different stages to toggle features.

Why?

1. Quickly enable and disable features in a project.
2. Provide simplest A/B testing.
3. Create staging, test and production environments.
4. Converts to clear pure boolean.
5. Enables continuity.
6. Enables Gitops.
7. Enables package.json branching.

What?

flgs is a simple feature flagging manager. It looks up different places for specific configurations and imports them. Possible options are:

• package.json
• flgs.json
• command line parameters
• global array
• class constructor

The order of priorization is package > file > cli > global > constructor.

Regard: A flag is set or unset. Because of this maxime flgs converts all values to either true or false based on an own strategy:

• true, "true", 1, "1", "on", "yes", "enable" will be interpreted as set
• a function or an object as a value for a flag, even if the are empty, will be interpreted as set
• null will be interpreted as unset
• all other values and types will be interpreted as unset

How?

First, install the package via NPM.

$ npm install --save ffm

Second, import the package and instantiate FFM.

const Flgs = require('flgs')
let flgs = new Flgs()

Third, use it in a simple if clause:

if (flgs.isSet('bluecolors')) {
    //  new behaviour
}
else {
    //  old behaviour
}

An example for package.json located in the root of the importing project:

{
  "featureflags": {
    "bluecolors": true,
    "redcolors": false,
    "greencolors": false,
    "violetcolors": {},
    "orangecolors": [
      "a",
      "b"
    ]
  }
}

An example for flgs.json located in the root of the importing project:

{
    "greencolors": false,
    "redcolors": true,
    "bluecolors": true,
    "violetcolors": false,
    "orangecolors": false
}

An example for the command line interface, provided via scripts of package.json in the root of the importing project. The cli argument must start with FFM_:

{
  "scripts": {
    "flagging": "node index.js FFM_BLUECOLORS"
  }
}

An example for a global array:

const _FMM = {
    "bluecolors": true
}

An example for a default configuration:

let flgs = new Flgs({
    "bluecolors": true
})

License

Copyright (c) 2022 Mark Lubkowitz (https://mlu.io/)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.