Bullet Train Client

The SDK clients for web and React Native for https://bullet-train.io/. Bullet Train allows you to manage feature flags and remote config across multiple projects, environments and organisations.

Getting Started

For full documentation visit https://docs.bullet-train.io/clients/javascript/

These instructions will get you a copy of the project up and running on your local machine for development and testing purposes. See running in production for notes on how to deploy the project on a live system.

Usage

Web:

npm i bullet-train-client --save

React Native:

npm i react-native-bullet-train --save

Retrieving feature flags for your project

import bulletTrain from "bullet-train-client or react-native-bullet-train"; //Add this line if you're using bulletTrain via npm

bulletTrain.identify("bullet_train_sample_user");

bulletTrain.init({
	environmentID:"<YOUR_ENVIRONMENT_KEY>",
    cacheFlags: true,
	onChange: (oldFlags,params)=>{ //Occurs whenever flags are changed
	
		const {isFromServer} = params; //determines if the update came from the server or local cached storage
		
		//Check for a feature
		if (bulletTrain.hasFeature("myCoolFeature")){
			myCoolFeature();
		}
				
		//Or, use the value of a feature
		const bannerSize = bulletTrain.getValue("bannerSize");
		
		//Check whether value has changed
		const bannerSizeOld = oldFlags["bannerSize"] && oldFlags["bannerSize"].value;
		if (bannerSize !== bannerSizeOld) {
		
		}

	}
});

Initialisation options

Property	Description	Required	Default Value
environmentID	Defines which project environment you wish to get flags for. example ACME Project - Staging.	YES	null
onChange	Your callback function for when the flags are retrieved (flags,{isFromServer:true/false})=>{...}	YES	null
onError	Callback function on failure to retrieve flags. (error)=>{...}		null
cacheFlags	Any time flags are retrieved they will be cached, flags and identities will then be retrieved from local storage before hitting the API ```		null
enableLogs	Enables logging for key bullet train events ```		null
defaultFlags	Allows you define default features, these will all be overridden on first retrieval of features.		null
preventFetch	Use this if you want to prevent fetching on init(), e.g. if you want to do some initialisation or call identify.		false
api	Use this property to define where you're getting feature flags from, e.g. if you're self hosting.		https://api.bullet-train.io/api/v1/

Available Functions

Property	Description
init	Initialise the sdk against a particular environment
hasFeature(key)	Get the value of a particular feature e.g. bulletTrain.hasFeature("powerUserFeature") // true
getValue(key)	Get the value of a particular feature e.g. bulletTrain.getValue("font_size") // 10
getTrait(key)	Once used with an identified user you can get the value of any trait that is set for them e.g. bulletTrain.getTrait("accepted_cookie_policy")
setTrait(key, value)	Once used with an identified user you can set the value of any trait relevant to them e.g. bulletTrain.setTrait("accepted_cookie_policy", true)
incrementTrait(key, value)	You can also increment/decrement a particular trait them e.g. bulletTrain.incrementTrait("click_count", 1)
getSegments(key)	returns a map of segments the user belongs to
startListening(ticks=1000)	Poll the api for changes every x milliseconds
stopListening()	Stop polling the api
getFlags()	Trigger a manual fetch of the environment features, if a user is identified it will fetch their features
identify(userId)	Identify as a user, this will create a user for your environment in the dashboard if they don't exist, it will also trigger a call to getFlags()
logout()	Stop identifying as a user, this will trigger a call to getFlags()

Serverside Support with Next.js

This library now supports server side rendering! In order to use this, use the following instead of the standard bullet-train-client:

import bulletTrain from 'bullet-train-client/isomorphic';

Contributing

Please read CONTRIBUTING.md for details on our code of conduct, and the process for submitting pull requests to us.

Getting Help

If you encounter a bug or feature request we would like to hear about it. Before you submit an issue please search existing issues in order to prevent duplicates.

Get in touch

If you have any questions about our projects you can email [email protected].

Useful links

Website

Documentation

Code Examples

Youtube Tutorials