flagsmith-react
Flagsmith SDK for React Single Page Applications (SPA).
Contents
Installation
Using npm
npm install flagsmith-react
Using yarn
yarn add flagsmith-react
Getting Started
Configure the SDK by wrapping your application in a FlagsmithProvider
element:
// src/index.js
import React from 'react';
import ReactDOM from 'react-dom';
import {FlagsmithProvider} from 'flagsmith-react';
import App from './App';
ReactDOM.render(
<FlagsmithProvider
environmentId="YOUR_FLAGSMITH_ENVIRONMENT_ID"
>
<App />
</FlagsmithProvider>,
document.getElementById('app')
);
The Flagsmith Provider
defaults to using the vanilla JavaScript Flagsmith SDK. To support alternative SDK, for example the React Native variant, a specific provider can be supplied as a parameter, for example
// src/index.js
import React from 'react';
import ReactDOM from 'react-dom';
import {FlagsmithProvider} from 'flagsmith-react';
import flagsmith from 'react-native-flagsmith';
import App from './App';
ReactDOM.render(
<FlagsmithProvider
environmentId="YOUR_FLAGSMITH_ENVIRONMENT_ID"
flagsmith={ flagsmith }
>
<App />
</FlagsmithProvider>,
document.getElementById('app')
);
Use the useFlagsmith
hook in your components to access the Flagsmith state (isLoading
, isIdentified
, isError
) and feature flag and remote configuration methods (hasFeature
, getValue
etc.)
import React from 'react';
import { useFlagsmith } from 'flagsmith-react';
function App() {
const {
isLoading,
isError,
hasFeature,
getValue
} = useFlagsmith();
if (isLoading) {
return <div>Flagsith state is loading...</div>
}
if (isError) {
return <div>Failed to load Flagsmith state!</div>
}
const hasExtraText = hasFeature('extra_text')
const theValue = getValue('example_value')
return <div>
<div>The value is {theValue}.</div>
{
hasExtraText && <div>Here is the extra text feature</div>
}
</div>
}
export default App;
API Reference
The
flagsmith-react
API is modelled on the Flagsmith Javascript integration, the documentation for which can be found here for further reference.
FlagsmithProvider
<FlagsmithProvider
environmentId
flagsmith
asyncStorage
cacheFlags
defaultFlags
preventFetch
api>
</FlagsmithProvider>
Use the FlagsmithProvider component to wrap your application and allow child elements to access the Flagsmith functionality using the 'useFlagsmith' hook function.
useFlagsmith
const {
isLoading,
isIdentified,
isError,
identify,
hasFeature,
getValue,
subscribe
} = useFlagsmith();
Use the useFlagsmith
hook in your components to access the Flagsmith state and methods.
isLoading: boolean
True if the Flagsmith state is loading, false is the state is loaded and usable. You should not try accessing the state (i.e. feature flags and remote configuration) until this is false and the state is loaded.
isIdentified: boolean
True if Flagsmith has been configured to use a specific identity when resolving flags and remote configuration, false otherwise.
See identify for more information.
isListening: boolean
True if Flagsmith is configured to listen for updates. See startListening for more details.
isError: boolean
True if the Flagsmith integration is in an errored state (e.g. the server could not be reached). False otherwise.
identify
await identify(identity)
Passes the supplied identity to the Flagsmith backend to be used when resolving feature flags and remote configuration. This causes an update in the state, which is an async action. Use the isIdentified flag to determine when the state has been re-loaded, or use subscribe to receive an update notification.
logout
await logout()
Remove any identity associated with the Flagsmith client. Use the isIdentified flag to determine when the state has been re-loaded, or use subscribe to receive an update notification.
hasFeature
hasFeature(key)
Determines is the feature specified key
is set or not.
getValue
getValue(key)
Gets the current value of the remote configuration item specified by the key
.
startListening
startListening(interval = 1000)
Begin listening for backend configuration changes. The polling interval is specified in mS. Use isListening to determine the current listening state, and subscribe to be notified of updates.
stopListening
stopListening()
Stop listening (polling) for configuration changes.
subscribe
subscribe(callback)
Registers a callback with Flagsmith that will be triggered any time a new configuration is available, for example after loading is complete, or when a new user is identified. This can be used to update any configuration state in components using Flagsmith, per the following example.
import { useEffect, useState } from 'react'
import logo from './logo.svg';
import './App.css';
import { useFlagsmith } from 'flagsmith-react'
function App() {
const { isLoading, isError, getValue, identify, subscribe } = useFlagsmith()
const [val, setVal] = useState()
useEffect(() => {
if(!isLoading) {
identify('someone@somewhere.com')
}
}, [isLoading, identify])
const handleChange = () => {
setVal( getValue('val') )
}
subscribe(handleChange)
return (
<>
{
!isLoading &&
<div className="App">
<header className="App-header">
<img src={logo} className="App-logo" alt="logo" />
<p>
Edit <code>src/App.js</code> and save to reload.
</p>
<a
className="App-link"
href="https://reactjs.org"
target="_blank"
rel="noopener noreferrer"
>
Learn React
</a>
{
isError && <h3>Flagsmith failed to load</h3>
}
{
val && <h1>{val}</h1>
}
</header>
</div>
}
</>
);
}
export default App;
getFlags
await getFlags()
Forces a fetch of the current flags.
getTrait
getTrait(key)
Can only be used once a user has been identified, to get the value of the specified trait for that user.
setTrait
await setTrait(key, value)
Can only be used once a user has been identified, to set the value of the specified trait for that user.
setTraits
await setTraits(traits)
Can only be used once a user has been identified, to set the value of the multiple traits for that user. Traits set to a value of null
will be removed.
incrementTrait
await incrementTrait(key, incrementBy)
Can only be used once a user has been identified, used to increment (or decrement) the specified trait for that user.