Flagsmith SDK for React Single Page Applications (SPA).
Using npm
npm install flagsmith-reactUsing yarn
yarn add flagsmith-reactConfigure 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;The
flagsmith-reactAPI is modelled on the Flagsmith Javascript integration, the documentation for which can be found here for further reference.
<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.
const {
isLoading,
isIdentified,
isError,
identify,
hasFeature,
getValue,
subscribe
} = useFlagsmith();Use the useFlagsmith hook in your components to access the Flagsmith state and methods.
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.
True if Flagsmith has been configured to use a specific identity when resolving flags and remote configuration, false otherwise.
See identify for more information.
True if Flagsmith is configured to listen for updates. See startListening for more details.
True if the Flagsmith integration is in an errored state (e.g. the server could not be reached). False otherwise.
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.
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(key)Determines is the feature specified key is set or not.
getValue(key)Gets the current value of the remote configuration item specified by the key.
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()Stop listening (polling) for configuration changes.
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;await getFlags()Forces a fetch of the current flags.
getTrait(key)Can only be used once a user has been identified, to get the value of the specified trait for that user.
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.
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.
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.